v3.26.3
Fees and Expenses
Sep. 28, 2026
LARGE CAP FUND | SIIT LARGE CAP FUND  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.40%

Distribution (12b‑1) Fees

None

Other Expenses

0.07%

Total Annual Fund Operating Expenses

0.47%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Large Cap Fund — Class A Shares

$48

$151

$263

$591
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 81% of the average value of its portfolio.
Portfolio Turnover, Rate 81.00%
LARGE CAP DISCIPLINED EQUITY FUND | SIIT LARGE CAP DISCIPLINED EQUITY FUND  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.40%

Distribution (12b‑1) Fees

None

Other Expenses

0.07%

Total Annual Fund Operating Expenses

0.47%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Large Cap Disciplined Equity Fund — Class A Shares

$48

$151

$263

$591
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 111% of the average value of its portfolio.
Portfolio Turnover, Rate 111.00%
LARGE CAP INDEX FUND | SIIT LARGE CAP INDEX FUND  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.05%

Distribution (12b‑1) Fees

None

Other Expenses

0.08%

Total Annual Fund Operating Expenses

0.13%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Large Cap Index Fund — Class A Shares

$13

$42

$73

$166
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 10% of the average value of its portfolio.
Portfolio Turnover, Rate 10.00%
S&P 500 INDEX FUND | SIIT S&P 500 Index Fund  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.03%

Distribution (12b‑1) Fees

None

Other Expenses

0.09%

Total Annual Fund Operating Expenses

0.12%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

S&P 500 Index Fund — Class A Shares

$12

$39

$68

$154
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 5% of the average value of its portfolio.
Portfolio Turnover, Rate 5.00%
EXTENDED MARKET INDEX FUND | SIIT Extended Market Index Fund  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.12%

Distribution (12b‑1) Fees

None

Other Expenses

0.08%

Total Annual Fund Operating Expenses

0.20%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Extended Market Index Fund — Class A Shares

$20

$64

$113

$255
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund will pay transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 23% of the average value of its portfolio.
Portfolio Turnover, Rate 23.00%
SMALL CAP FUND | SIIT SMALL CAP FUND  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.65%

Distribution (12b‑1) Fees

None

Other Expenses

0.07%

Total Annual Fund Operating Expenses

0.72%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Small Cap Fund — Class A Shares

$74

$230

$401

$894
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 125% of the average value of its portfolio.
Portfolio Turnover, Rate 125.00%
SMALL CAP II FUND | SIIT Small Cap II Fund  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.65%

Distribution (12b‑1) Fees

None

Other Expenses

0.07%

Total Annual Fund Operating Expenses

0.72%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Small Cap II Fund — Class A Shares

$74

$230

$401

$894
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund will pay transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 104% of the average value of its portfolio.
Portfolio Turnover, Rate 104.00%
SMALL/MID CAP EQUITY FUND | SIIT SMALL MID CAP EQUITY FUND  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.65%

Distribution (12b‑1) Fees

None

Other Expenses

0.07%

Total Annual Fund Operating Expenses

0.72%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Small/Mid Cap Equity Fund — Class A Shares

$74

$230

$401

$894
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 76% of the average value of its portfolio.
Portfolio Turnover, Rate 76.00%
U.S. EQUITY FACTOR ALLOCATION FUND | SIIT U.S. Equity Factor Allocation Fund  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.25%

Distribution (12b‑1) Fees

None

Other Expenses

0.06%

Total Annual Fund Operating Expenses

0.31%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

U.S. Equity Factor Allocation Fund — Class A Shares

$32

$100

$174

$393
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 45% of the average value of its portfolio.
Portfolio Turnover, Rate 45.00%
U.S. MANAGED VOLATILITY FUND | SIIT U.S. Managed Volatility Fund  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.55%

Distribution (12b‑1) Fees

None

Other Expenses

0.07%

Total Annual Fund Operating Expenses

0.62%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

U.S. Managed Volatility Fund — Class A Shares

$63

$199

$346

$774
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 69% of the average value of its portfolio.
Portfolio Turnover, Rate 69.00%
GLOBAL MANAGED VOLATILITY FUND | SIIT Global Managed Volatility Fund  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.65%

Distribution (12b‑1) Fees

None

Other Expenses

0.07%

Total Annual Fund Operating Expenses

0.72%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Global Managed Volatility Fund — Class A Shares

$74

$230

$401

$894
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 43% of the average value of its portfolio.
Portfolio Turnover, Rate 43.00%
WORLD EQUITY EX-US FUND | SIIT WORLD EQUITY EX-US FUND  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.55%

Distribution (12b‑1) Fees

None

Other Expenses

0.08%

Total Annual Fund Operating Expenses

0.63%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

World Equity Ex-US Fund — Class A Shares

$64

$202

$351

$786
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 69% of the average value of its portfolio.
Portfolio Turnover, Rate 69.00%
SCREENED WORLD EQUITY EX-US FUND | SIIT Screened World Equity Ex-US Fund  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.65%

Distribution (12b‑1) Fees

None

Other Expenses

0.18%

Total Annual Fund Operating Expenses

0.83%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Screened World Equity Ex-US Fund — Class A Shares

$85

$265

$460

$1,025
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 102% of the average value of its portfolio.
Portfolio Turnover, Rate 102.00%
EMERGING MARKETS EQUITY FUND | SIIT EMERGING MARKETS EQUITY FUND  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.85%

Distribution (12b‑1) Fees

None

Other Expenses

0.17%

Total Annual Fund Operating Expenses

1.02%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Emerging Markets Equity Fund — Class A Shares

$104

$325

$563

$1,248
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund will pay transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 87% of the average value of its portfolio.
Portfolio Turnover, Rate 87.00%
OPPORTUNISTIC INCOME FUND | SIIT Opportunistic Income Fund  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.45%

Distribution (12b‑1) Fees

None

Other Expenses

0.11%

Total Annual Fund Operating Expenses

0.56%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Opportunistic Income Fund — Class A Shares

$57

$179

$313

$701
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 47% of the average value of its portfolio.
Portfolio Turnover, Rate 47.00%
CORE FIXED INCOME FUND | SIIT CORE FIXED INCOME  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.30%

Distribution (12b‑1) Fees

None

Other Expenses

0.07%

Total Annual Fund Operating Expenses

0.37%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Core Fixed Income Fund — Class A Shares

$38

$119

$208

$468
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 260% of the average value of its portfolio.
Portfolio Turnover, Rate 260.00%
HIGH YIELD BOND FUND | SIIT HIGH YIELD BOND FUND  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fund Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.49%

Distribution (12b‑1) Fees

None

Other Expenses

0.07%

Total Annual Fund Operating Expenses

0.56%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

High Yield Bond Fund — Class A Shares

$57

$179

$313

$701
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 68% of the average value of its portfolio.
Portfolio Turnover, Rate 68.00%
LONG DURATION FUND | SIIT LONG DURATION FUND  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.30%

Distribution (12b‑1) Fees

None

Other Expenses

0.08%

Total Annual Fund Operating Expenses

0.38%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Long Duration Fund — Class A Shares

$39

$122

$213

$480
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 131% of the average value of its portfolio.
Portfolio Turnover, Rate 131.00%
LONG DURATION CREDIT FUND | SIIT Long Duration Credit Fund  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.30%

Distribution (12b‑1) Fees

None

Other Expenses

0.07%

Total Annual Fund Operating Expenses

0.37%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Long Duration Credit Fund — Class A Shares

$38

$119

$208

$468
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund will incur transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 101% of the average value of its portfolio.
Portfolio Turnover, Rate 101.00%
ULTRA SHORT DURATION BOND FUND | SIIT Ultra Short Duration Bond Fund  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.15%

Distribution (12b‑1) Fees

None

Other Expenses

0.09%

Total Annual Fund Operating Expenses

0.24%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Ultra Short Duration Bond Fund — Class A Shares

$25

$77

$135

$306
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 73% of the average value of its portfolio.
Portfolio Turnover, Rate 73.00%
EMERGING MARKETS DEBT FUND | SIIT EMERGING MARKETS DEBT FUND  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.60%

Distribution (12b‑1) Fees

None

Other Expenses

0.10%

Total Annual Fund Operating Expenses

0.70%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Emerging Markets Debt Fund — Class A Shares

$72

$224

$390

$871
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 91% of the average value of its portfolio.
Portfolio Turnover, Rate 91.00%
REAL RETURN FUND | SIIT Real Return Fund  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.22%

Distribution (12b‑1) Fees

None

Other Expenses

0.06%

Total Annual Fund Operating Expenses

0.28%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Real Return Fund — Class A Shares

$29

$90

$157

$356
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 38% of the average value of its portfolio.
Portfolio Turnover, Rate 38.00%
LIMITED DURATION BOND FUND | SIIT Limited Duration Bond Fund  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.25%

Distribution (12b‑1) Fees

None

Other Expenses

0.07%

Total Annual Fund Operating Expenses

0.32%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Limited Duration Bond Fund — Class A Shares

$33

$103

$180

$406
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 181% of the average value of its portfolio.
Portfolio Turnover, Rate 181.00%
INTERMEDIATE DURATION CREDIT FUND | SIIT Intermediate Duration Credit Fund  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees

0.25%

Distribution (12b‑1) Fees

None

Other Expenses

0.07%

Total Annual Fund Operating Expenses

0.32%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Intermediate Duration Credit Fund — Class A Shares

$33

$103

$180

$406
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund will incur transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 148% of the average of its portfolio.
Portfolio Turnover, Rate 148.00%
DYNAMIC ASSET ALLOCATION FUND | SIIT Dynamic Asset Allocation Fund  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees (of the Fund and Subsidiary)

Management Fees of the Fund

0.60%

Management Fees of the Subsidiary

None

Total Management Fees

0.60%

Distribution (12b‑1) Fees

None

Other Expenses (of the Fund and Subsidiary)

Other Expenses of the Fund

0.07%

Other Expenses of the Subsidiary

None

Total Annual Fund Operating Expenses

0.67%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Dynamic Asset Allocation Fund — Class A Shares

$68

$214

$373

$835
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 19% of the average value of its portfolio.
Portfolio Turnover, Rate 19.00%
MULTI-ASSET REAL RETURN FUND | SIIT Multi-Asset Real Return Fund  
Prospectus [Line Items]  
Expense Heading [Optional Text] Fees and Expenses
Expense Narrative [Text Block]

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.
Operating Expenses Caption [Optional Text] ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Annual Fund Operating Expenses [Table]

(expenses that you pay each year as a percentage of the value of your investment)

Class A Shares

Management Fees (of the Fund and Subsidiary)

Management Fees of the Fund

0.55%

Management Fees of the Subsidiary

None

Total Management Fees

0.55%

Distribution (12b‑1) Fees

None

Other Expenses (of the Fund and Subsidiary)

Other Expenses of the Fund

0.08%

Other Expenses of the Subsidiary

None

Dividends on Shorts

0.03%

Interest Expense on Reverse Repurchase Agreements

0.00%

Total Other Expenses

0.11%

Total Annual Fund Operating Expenses

0.66%
Expense Example [Heading] EXAMPLE
Expense Example Narrative [Text Block]

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

Expense Example by, Year, Caption [Text] Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, With Redemption [Table]

1 Year

3 Years

5 Years

10 Years

Multi-Asset Real Return Fund — Class A Shares

$67

$211

$368

$822
Portfolio Turnover [Heading] PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]

The Fund will pay transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher

taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 55% of the average value of its portfolio.
Portfolio Turnover, Rate 55.00%