Shareholder Report
|
6 Months Ended |
|
Jun. 30, 2025
USD ($)
Holding
|
|---|
| Shareholder Report [Line Items] |
|
|
| Document Type |
N-CSRS
|
|
| Amendment Flag |
false
|
|
| Registrant Name |
BlackRock Series Fund, Inc.
|
|
| Entity Central Index Key |
0000319108
|
|
| Entity Investment Company Type |
N-1A
|
|
| Document Period End Date |
Jun. 30, 2025
|
|
| C000010830 |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
BlackRock Advantage Large Cap Core Portfolio
|
|
| Trading Symbol |
LGCCS
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about BlackRock Advantage Large Cap Core Portfolio (the “Fund”) for the period of January 1, 2025 to June 30, 2025.
|
|
| Shareholder Report Annual or Semi-Annual |
Semi-Annual Shareholder Report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 537-4942.
|
|
| Additional Information Website |
blackrock.com/fundreports
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?(based on a hypothetical $10,000 investment) Fund name | Costs of a $10,000 investment | Costs paid as a percentage of a $10,000 investment |
|---|
BlackRock Advantage Large Cap Core Portfolio | $25 | 0.48%Footnote Reference(a) |
|---|
| Footnote | Description | Footnote(a) | Annualized. |
|
|
| Expenses Paid, Amount |
$ 25
|
|
| Expense Ratio, Percent |
0.48%
|
[1] |
| AssetsNet |
$ 214,542,027
|
|
| Holdings Count | Holding |
192
|
|
| InvestmentCompanyPortfolioTurnover |
57.00%
|
|
| Holdings [Text Block] |
SectorFootnote Reference(a) | Percent of
Net Assets |
|---|
Information Technology........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 32.6% | Financials........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 13.9 | Consumer Discretionary........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 12.0 | Health Care........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 10.6 | Communication Services........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 9.7 | Industrials........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 8.2 | Consumer Staples........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 4.8 | Energy........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 2.6 | Real Estate........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 2.0 | Materials........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 1.3 | Utilities........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 1.3 | Short-Term Securities........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 2.3 | Liabilities in Excess of Other Assets........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | (1.3) |
| Footnote | Description | Footnote(a) | For purposes of this report, sector sub-classifications may differ from those utilized by the Fund for compliance purposes. |
|
|
| C000010829 |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
BlackRock Balanced Portfolio
|
|
| Trading Symbol |
BLCPS
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about BlackRock Balanced Portfolio (the “Fund”) (formerly known as BlackRock Sustainable Balanced Portfolio) for the period of January 1, 2025 to June 30, 2025.
|
|
| Shareholder Report Annual or Semi-Annual |
Semi-Annual Shareholder Report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 537-4942.
|
|
| Additional Information Website |
blackrock.com/fundreports
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?(based on a hypothetical $10,000 investment) Fund name | Costs of a $10,000 investment | Costs paid as a percentage of a $10,000 investment |
|---|
BlackRock Balanced Portfolio | $25 | 0.48%Footnote Reference(a) |
|---|
| Footnote | Description | Footnote(a) | Annualized. |
|
|
| Expenses Paid, Amount |
$ 25
|
|
| Expense Ratio, Percent |
0.48%
|
[2] |
| AssetsNet |
$ 463,802,882
|
|
| Holdings Count | Holding |
1,691
|
|
| InvestmentCompanyPortfolioTurnover |
52.00%
|
|
| Holdings [Text Block] |
Investment Type | Percent of Total InvestmentsFootnote Reference(a) |
|---|
Common Stocks........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 60.2% | Corporate Bonds........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 20.7 | U.S. Treasury Obligations........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 10.9 | U.S. Government Sponsored Agency Securities........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 7.8 | Asset-Backed Securities........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 0.1 | Foreign Government Obligations........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 0.1 | Non-Agency Mortgage-Backed Securities........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 0.1 | Preferred Securities........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 0.1 | Other Interests........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | - |
| Footnote | Description | Footnote(a) | Excludes short-term securities, short investments and options, if any. |
|
|
| C000010833 |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
BlackRock Capital Appreciation Portfolio
|
|
| Trading Symbol |
FDGRS
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about BlackRock Capital Appreciation Portfolio (the “Fund”) for the period of January 1, 2025 to June 30, 2025.
|
|
| Shareholder Report Annual or Semi-Annual |
Semi-Annual Shareholder Report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 537-4942.
|
|
| Additional Information Website |
blackrock.com/fundreports
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?(based on a hypothetical $10,000 investment) Fund name | Costs of a $10,000 investment | Costs paid as a percentage of a $10,000 investment |
|---|
BlackRock Capital Appreciation Portfolio | $24 | 0.47%Footnote Reference(a) |
|---|
| Footnote | Description | Footnote(a) | Annualized. |
|
|
| Expenses Paid, Amount |
$ 24
|
|
| Expense Ratio, Percent |
0.47%
|
[3] |
| AssetsNet |
$ 262,015,473
|
|
| Holdings Count | Holding |
39
|
|
| InvestmentCompanyPortfolioTurnover |
18.00%
|
|
| Holdings [Text Block] |
SectorFootnote Reference(a) | Percent of
Net Assets |
|---|
Information Technology........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 47.0% | Communication Services........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 15.5 | Consumer Discretionary........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 15.0 | Financials........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 8.3 | Health Care........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 7.5 | Industrials........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 5.7 | Materials........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 0.8 | Real Estate........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 0.3 | Short-Term Securities........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 8.3 | Liabilities in Excess of Other Assets........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | (8.4) |
| Footnote | Description | Footnote(a) | For purposes of this report, sector sub-classifications may differ from those utilized by the Fund for compliance purposes. |
|
|
| C000010832 |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
BlackRock Global Allocation Portfolio
|
|
| Trading Symbol |
GLALS
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about BlackRock Global Allocation Portfolio (the “Fund”) for the period of January 1, 2025 to June 30, 2025.
|
|
| Shareholder Report Annual or Semi-Annual |
Semi-Annual Shareholder Report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 537-4942.
|
|
| Material Fund Change Notice [Text Block] |
|
|
| Additional Information Website |
blackrock.com/fundreports
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?(based on a hypothetical $10,000 investment) Fund name | Costs of a $10,000 investment | Costs paid as a percentage of a $10,000 investment |
|---|
BlackRock Global Allocation Portfolio | $30 | 0.58%Footnote Reference(a) |
|---|
| Footnote | Description | Footnote(a) | Annualized. |
|
|
| Expenses Paid, Amount |
$ 30
|
|
| Expense Ratio, Percent |
0.58%
|
[4] |
| AssetsNet |
$ 154,842,938
|
|
| Holdings Count | Holding |
1,889
|
|
| InvestmentCompanyPortfolioTurnover |
66.00%
|
|
| Additional Fund Statistics [Text Block] |
Net Assets........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | $154,842,938 |
|---|
Number of Portfolio Holdings........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 1,889 |
|---|
Portfolio Turnover Rate........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 66% |
|---|
|
|
| Holdings [Text Block] |
| Percent of Total
InvestmentsFootnote Reference(a) |
|---|
Country/Geographic Region | Long | Short | Total |
|---|
United States........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 63.7% | -% | 63.7% | United Kingdom........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 5.9 | - | 5.9 | France........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 3.4 | - | 3.4 | Italy........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 2.9 | - | 2.9 | Germany........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 2.6 | - | 2.6 | Netherlands........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 2.4 | - | 2.4 | China........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 2.3 | - | 2.3 | Ireland........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 2.2 | - | 2.2 | Japan........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 2.0 | - | 2.0 | Canada........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 1.9 | - | 1.9 | OtherFootnote Reference(b)........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 10.7 | - | 10.7 | Total........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 100.0% | -% | 100.0% |
| Footnote | Description | Footnote(a) | Includes the gross market value of long and short securities and excludes short-term securities and options, if any. | Footnote(b) | Ten largest countries/geographic regions are presented. Additional countries/geographic regions are found in Other. |
|
|
| C000010836 |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
BlackRock Government Money Market Portfolio
|
|
| Trading Symbol |
MNRSV
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about BlackRock Government Money Market Portfolio (the “Fund”) for the period of January 1, 2025 to June 30, 2025.
|
|
| Shareholder Report Annual or Semi-Annual |
Semi-Annual Shareholder Report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 537-4942.
|
|
| Additional Information Website |
blackrock.com/fundreports
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?(based on a hypothetical $10,000 investment) Fund name | Costs of a $10,000 investment | Costs paid as a percentage of a $10,000 investment |
|---|
BlackRock Government Money Market Portfolio | $24 | 0.48%Footnote Reference(a) |
|---|
| Footnote | Description | Footnote(a) | Annualized. |
|
|
| Expenses Paid, Amount |
$ 24
|
|
| Expense Ratio, Percent |
0.48%
|
[5] |
| AssetsNet |
$ 107,982,461
|
|
| Holdings Count | Holding |
93
|
|
| Additional Fund Statistics [Text Block] |
Net Assets........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | $107,982,461 |
|---|
Number of Portfolio Holdings........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 93 |
|---|
Current seven-day yields as of June 30, 2025 (The 7-day SEC Yield may differ from the 7-Day Yield shown due to the fact that the 7-Day SEC Yield excludes distributed capital gains.) | 0 |
|---|
7-Day SEC Yield........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 3.96% |
|---|
7-Day Yield........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 3.96% |
|---|
|
|
| Holdings [Text Block] |
Asset Type | Percent of
Net Assets |
|---|
Repurchase Agreements........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 43.1% | U.S. Treasury Obligations........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 41.8 | U.S. Government Sponsored Agency Obligations........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | 16.0 | Liabilities in Excess of Other Assets........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | (0.9) |
|
|
|
|