Shareholder Report
|
6 Months Ended |
|
Apr. 30, 2026
USD ($)
Holding
|
|---|
| Shareholder Report [Line Items] |
|
|
| Document Type |
N-CSRS
|
|
| Amendment Flag |
false
|
|
| Registrant Name |
ALGER INSTITUTIONAL FUNDS
|
|
| Entity Central Index Key |
0000911415
|
|
| Entity Investment Company Type |
N-1A
|
|
| Document Period End Date |
Apr. 30, 2026
|
|
| C000174229 [Member] |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
Alger Capital Appreciation Institutional Fund
|
|
| Class Name |
Class Z-2
|
|
| Trading Symbol |
ACIZX
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about the Alger Capital Appreciation Institutional Fund (“Fund”) for the period from November 1, 2025 to April 30, 2026.
|
|
| Shareholder Report Annual or Semi-Annual |
semi-annual shareholder report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at www.alger.com/fundliterature. You can also request a copy of the semi-annual report by contacting us at (800) 992-3863.
|
|
| Additional Information Phone Number |
(800) 992-3863
|
|
| Additional Information Website |
www.alger.com/fundliterature
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
| Fund (Class/Ticker) |
Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
Alger Capital Appreciation Institutional Fund
(Class Z-2 / ACIZX) |
$42 |
0.84%(a) |
|
|
| Expenses Paid, Amount |
$ 42
|
|
| Expense Ratio, Percent |
0.84%
|
[1] |
| Net Assets |
$ 3,290,638,853
|
|
| Holdings Count | Holding |
85
|
[2] |
| Investment Company Portfolio Turnover |
32.82%
|
|
| Additional Fund Statistics [Text Block] |
Key Fund Statistics
The following table outlines key fund statistics as of the fiscal six-month period ended April 30, 2026.
| Fund net assets |
$3,290,638,853 |
| Total number of portfolio holdings1 |
85 |
| Portfolio turnover rate |
32.82% |
|
1
|
Number of portfolio holdings is calculated at the issuer level. Excludes Money Market Funds.
|
|
|
| Holdings [Text Block] |
Sector Allocation †
| Communication Services |
12.1% |
| Consumer Discretionary |
11.8% |
| Energy |
0.7% |
| Financials |
1.8% |
| Health Care |
7.2% |
| Industrials |
5.8% |
| Information Technology |
56.8% |
| Materials |
0.5% |
| Real Estate |
0.7% |
| Utilities |
2.0% |
| Short-Term Investments and Other Net Assets |
0.6% |
|
100.0% |
|
|
| C000025005 [Member] |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
Alger Capital Appreciation Institutional Fund
|
|
| Class Name |
Class R
|
|
| Trading Symbol |
ACARX
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about the Alger Capital Appreciation Institutional Fund (“Fund”) for the period from November 1, 2025 to April 30, 2026.
|
|
| Shareholder Report Annual or Semi-Annual |
semi-annual shareholder report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at www.alger.com/fundliterature. You can also request a copy of the semi-annual report by contacting us at (800) 992-3863.
|
|
| Additional Information Phone Number |
(800) 992-3863
|
|
| Additional Information Website |
www.alger.com/fundliterature
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
| Fund (Class/Ticker) |
Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
Alger Capital Appreciation Institutional Fund
(Class R / ACARX) |
$81 |
1.64%(a) |
|
|
| Expenses Paid, Amount |
$ 81
|
|
| Expense Ratio, Percent |
1.64%
|
[3] |
| Net Assets |
$ 3,290,638,853
|
|
| Holdings Count | Holding |
85
|
[4] |
| Investment Company Portfolio Turnover |
32.82%
|
|
| Additional Fund Statistics [Text Block] |
Key Fund Statistics
The following table outlines key fund statistics as of the fiscal six-month period ended April 30, 2026.
| Fund net assets |
$3,290,638,853 |
| Total number of portfolio holdings1 |
85 |
| Portfolio turnover rate |
32.82% |
|
1
|
Number of portfolio holdings is calculated at the issuer level. Excludes Money Market Funds.
|
|
|
| Holdings [Text Block] |
Sector Allocation †
| Communication Services |
12.1% |
| Consumer Discretionary |
11.8% |
| Energy |
0.7% |
| Financials |
1.8% |
| Health Care |
7.2% |
| Industrials |
5.8% |
| Information Technology |
56.8% |
| Materials |
0.5% |
| Real Estate |
0.7% |
| Utilities |
2.0% |
| Short-Term Investments and Other Net Assets |
0.6% |
|
100.0% |
|
|
| C000179523 [Member] |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
Alger Capital Appreciation Institutional Fund
|
|
| Class Name |
Class Y
|
|
| Trading Symbol |
ACAYX
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about the Alger Capital Appreciation Institutional Fund (“Fund”) for the period from November 1, 2025 to April 30, 2026.
|
|
| Shareholder Report Annual or Semi-Annual |
semi-annual shareholder report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at www.alger.com/fundliterature. You can also request a copy of the semi-annual report by contacting us at (800) 992-3863.
|
|
| Additional Information Phone Number |
(800) 992-3863
|
|
| Additional Information Website |
www.alger.com/fundliterature
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
| Fund (Class/Ticker) |
Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
Alger Capital Appreciation Institutional Fund
(Class Y / ACAYX) |
$41 |
0.82%(a) |
|
|
| Expenses Paid, Amount |
$ 41
|
|
| Expense Ratio, Percent |
0.82%
|
[5] |
| Net Assets |
$ 3,290,638,853
|
|
| Holdings Count | Holding |
85
|
[6] |
| Investment Company Portfolio Turnover |
32.82%
|
|
| Additional Fund Statistics [Text Block] |
Key Fund Statistics
The following table outlines key fund statistics as of the fiscal six-month period ended April 30, 2026.
| Fund net assets |
$3,290,638,853 |
| Total number of portfolio holdings1 |
85 |
| Portfolio turnover rate |
32.82% |
|
1
|
Number of portfolio holdings is calculated at the issuer level. Excludes Money Market Funds.
|
|
|
| Holdings [Text Block] |
Sector Allocation †
| Communication Services |
12.1% |
| Consumer Discretionary |
11.8% |
| Energy |
0.7% |
| Financials |
1.8% |
| Health Care |
7.2% |
| Industrials |
5.8% |
| Information Technology |
56.8% |
| Materials |
0.5% |
| Real Estate |
0.7% |
| Utilities |
2.0% |
| Short-Term Investments and Other Net Assets |
0.6% |
|
100.0% |
|
|
| C000025004 [Member] |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
Alger Capital Appreciation Institutional Fund
|
|
| Class Name |
Class I
|
|
| Trading Symbol |
ALARX
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about the Alger Capital Appreciation Institutional Fund (“Fund”) for the period from November 1, 2025 to April 30, 2026.
|
|
| Shareholder Report Annual or Semi-Annual |
semi-annual shareholder report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at www.alger.com/fundliterature. You can also request a copy of the semi-annual report by contacting us at (800) 992-3863.
|
|
| Additional Information Phone Number |
(800) 992-3863
|
|
| Additional Information Website |
www.alger.com/fundliterature
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
| Fund (Class/Ticker) |
Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
Alger Capital Appreciation Institutional Fund
(Class I / ALARX) |
$60 |
1.20%(a) |
|
|
| Expenses Paid, Amount |
$ 60
|
|
| Expense Ratio, Percent |
1.20%
|
[7] |
| Net Assets |
$ 3,290,638,853
|
|
| Holdings Count | Holding |
85
|
[8] |
| Investment Company Portfolio Turnover |
32.82%
|
|
| Additional Fund Statistics [Text Block] |
Key Fund Statistics
The following table outlines key fund statistics as of the fiscal six-month period ended April 30, 2026.
| Fund net assets |
$3,290,638,853 |
| Total number of portfolio holdings1 |
85 |
| Portfolio turnover rate |
32.82% |
|
1
|
Number of portfolio holdings is calculated at the issuer level. Excludes Money Market Funds.
|
|
|
| Holdings [Text Block] |
Sector Allocation †
| Communication Services |
12.1% |
| Consumer Discretionary |
11.8% |
| Energy |
0.7% |
| Financials |
1.8% |
| Health Care |
7.2% |
| Industrials |
5.8% |
| Information Technology |
56.8% |
| Materials |
0.5% |
| Real Estate |
0.7% |
| Utilities |
2.0% |
| Short-Term Investments and Other Net Assets |
0.6% |
|
100.0% |
|
|
| C000025002 [Member] |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
Alger Mid Cap Growth Institutional Fund
|
|
| Class Name |
Class I
|
|
| Trading Symbol |
ALMRX
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about the Alger Mid Cap Growth Institutional Fund (“Fund”) for the period from November 1, 2025 to April 30, 2026.
|
|
| Shareholder Report Annual or Semi-Annual |
semi-annual shareholder report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at www.alger.com/fundliterature. You can also request a copy of the semi-annual report by contacting us at (800) 992-3863.
|
|
| Additional Information Phone Number |
(800) 992-3863
|
|
| Additional Information Website |
www.alger.com/fundliterature
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
| Fund (Class/Ticker) |
Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
Alger Mid Cap Growth Institutional Fund
(Class I / ALMRX) |
$62 |
1.26%(a) |
|
|
| Expenses Paid, Amount |
$ 62
|
|
| Expense Ratio, Percent |
1.26%
|
[9] |
| Net Assets |
$ 54,332,448
|
|
| Holdings Count | Holding |
68
|
[10] |
| Investment Company Portfolio Turnover |
42.82%
|
|
| Additional Fund Statistics [Text Block] |
Key Fund Statistics
The following table outlines key fund statistics as of the fiscal six-month period ended April 30, 2026.
| Fund net assets |
$54,332,448 |
| Total number of portfolio holdings1 |
68 |
| Portfolio turnover rate |
42.82% |
|
1
|
Number of portfolio holdings is calculated at the issuer level. Excludes Money Market Funds.
|
|
|
| Holdings [Text Block] |
Sector Allocation †
| Communication Services |
3.8% |
| Consumer Discretionary |
13.0% |
| Consumer Staples |
2.7% |
| Energy |
0.9% |
| Financials |
6.9% |
| Health Care |
13.1% |
| Industrials |
28.8% |
| Information Technology |
22.3% |
| Materials |
1.7% |
| Real Estate |
2.6% |
| Utilities |
2.3% |
| Short-Term Investments and Other Net Assets |
1.9% |
|
100.0% |
|
|
| C000025003 [Member] |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
Alger Mid Cap Growth Institutional Fund
|
|
| Class Name |
Class R
|
|
| Trading Symbol |
AGIRX
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about the Alger Mid Cap Growth Institutional Fund (“Fund”) for the period from November 1, 2025 to April 30, 2026.
|
|
| Shareholder Report Annual or Semi-Annual |
semi-annual shareholder report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at www.alger.com/fundliterature. You can also request a copy of the semi-annual report by contacting us at (800) 992-3863.
|
|
| Additional Information Phone Number |
(800) 992-3863
|
|
| Additional Information Website |
www.alger.com/fundliterature
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
| Fund (Class/Ticker) |
Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
Alger Mid Cap Growth Institutional Fund
(Class R / AGIRX) |
$92 |
1.89%(a) |
|
|
| Expenses Paid, Amount |
$ 92
|
|
| Expense Ratio, Percent |
1.89%
|
[11] |
| Net Assets |
$ 54,332,448
|
|
| Holdings Count | Holding |
68
|
[12] |
| Investment Company Portfolio Turnover |
42.82%
|
|
| Additional Fund Statistics [Text Block] |
Key Fund Statistics
The following table outlines key fund statistics as of the fiscal six-month period ended April 30, 2026.
| Fund net assets |
$54,332,448 |
| Total number of portfolio holdings1 |
68 |
| Portfolio turnover rate |
42.82% |
|
1
|
Number of portfolio holdings is calculated at the issuer level. Excludes Money Market Funds.
|
|
|
| Holdings [Text Block] |
Sector Allocation †
| Communication Services |
3.8% |
| Consumer Discretionary |
13.0% |
| Consumer Staples |
2.7% |
| Energy |
0.9% |
| Financials |
6.9% |
| Health Care |
13.1% |
| Industrials |
28.8% |
| Information Technology |
22.3% |
| Materials |
1.7% |
| Real Estate |
2.6% |
| Utilities |
2.3% |
| Short-Term Investments and Other Net Assets |
1.9% |
|
100.0% |
|
|
| C000174228 [Member] |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
Alger Mid Cap Growth Institutional Fund
|
|
| Class Name |
Class Z-2
|
|
| Trading Symbol |
ALMZX
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about the Alger Mid Cap Growth Institutional Fund (“Fund”) for the period from November 1, 2025 to April 30, 2026.
|
|
| Shareholder Report Annual or Semi-Annual |
semi-annual shareholder report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at www.alger.com/fundliterature. You can also request a copy of the semi-annual report by contacting us at (800) 992-3863.
|
|
| Additional Information Phone Number |
(800) 992-3863
|
|
| Additional Information Website |
www.alger.com/fundliterature
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
| Fund (Class/Ticker) |
Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
Alger Mid Cap Growth Institutional Fund
(Class Z-2 / ALMZX) |
$49 |
1.01%(a) |
|
|
| Expenses Paid, Amount |
$ 49
|
|
| Expense Ratio, Percent |
1.01%
|
[13] |
| Net Assets |
$ 54,332,448
|
|
| Holdings Count | Holding |
68
|
[14] |
| Investment Company Portfolio Turnover |
42.82%
|
|
| Additional Fund Statistics [Text Block] |
Key Fund Statistics
The following table outlines key fund statistics as of the fiscal six-month period ended April 30, 2026.
| Fund net assets |
$54,332,448 |
| Total number of portfolio holdings1 |
68 |
| Portfolio turnover rate |
42.82% |
|
1
|
Number of portfolio holdings is calculated at the issuer level. Excludes Money Market Funds.
|
|
|
| Holdings [Text Block] |
Sector Allocation †
| Communication Services |
3.8% |
| Consumer Discretionary |
13.0% |
| Consumer Staples |
2.7% |
| Energy |
0.9% |
| Financials |
6.9% |
| Health Care |
13.1% |
| Industrials |
28.8% |
| Information Technology |
22.3% |
| Materials |
1.7% |
| Real Estate |
2.6% |
| Utilities |
2.3% |
| Short-Term Investments and Other Net Assets |
1.9% |
|
100.0% |
|
|
| C000172687 [Member] |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
Alger Small Cap Growth Institutional Fund
|
|
| Class Name |
Class Z-2
|
|
| Trading Symbol |
AISZX
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about the Alger Small Cap Growth Institutional Fund (“Fund”) for the period from November 1, 2025 to April 30, 2026.
|
|
| Shareholder Report Annual or Semi-Annual |
semi-annual shareholder report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at www.alger.com/fundliterature. You can also request a copy of the semi-annual report by contacting us at (800) 992-3863.
|
|
| Additional Information Phone Number |
(800) 992-3863
|
|
| Additional Information Website |
www.alger.com/fundliterature
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
| Fund (Class/Ticker) |
Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
Alger Small Cap Growth Institutional Fund
(Class Z-2 / AISZX) |
$50 |
1.00%(a) |
|
|
| Expenses Paid, Amount |
$ 50
|
|
| Expense Ratio, Percent |
1.00%
|
[15] |
| Net Assets |
$ 71,328,354
|
|
| Holdings Count | Holding |
106
|
[16] |
| Investment Company Portfolio Turnover |
8.33%
|
|
| Additional Fund Statistics [Text Block] |
Key Fund Statistics
The following table outlines key fund statistics as of the fiscal six-month period ended April 30, 2026.
| Fund net assets |
$71,328,354 |
| Total number of portfolio holdings1 |
106 |
| Portfolio turnover rate |
8.33% |
|
1
|
Number of portfolio holdings is calculated at the issuer level. Excludes Money Market Funds.
|
|
|
| Holdings [Text Block] |
Sector Allocation †
| Communication Services |
0.7% |
| Consumer Discretionary |
6.8% |
| Consumer Staples |
1.5% |
| Financials |
5.9% |
| Health Care |
32.5% |
| Industrials |
28.4% |
| Information Technology |
23.3% |
| Materials |
0.1% |
| Utilities |
0.5% |
| Short-Term Investments and Other Net Assets |
0.3% |
|
100.0% |
|
|
| C000025001 [Member] |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
Alger Small Cap Growth Institutional Fund
|
|
| Class Name |
Class R
|
|
| Trading Symbol |
ASIRX
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about the Alger Small Cap Growth Institutional Fund (“Fund”) for the period from November 1, 2025 to April 30, 2026.
|
|
| Shareholder Report Annual or Semi-Annual |
semi-annual shareholder report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at www.alger.com/fundliterature. You can also request a copy of the semi-annual report by contacting us at (800) 992-3863.
|
|
| Additional Information Phone Number |
(800) 992-3863
|
|
| Additional Information Website |
www.alger.com/fundliterature
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
| Fund (Class/Ticker) |
Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
Alger Small Cap Growth Institutional Fund
(Class R / ASIRX) |
$94 |
1.89%(a) |
|
|
| Expenses Paid, Amount |
$ 94
|
|
| Expense Ratio, Percent |
1.89%
|
[17] |
| Net Assets |
$ 71,328,354
|
|
| Holdings Count | Holding |
106
|
[18] |
| Investment Company Portfolio Turnover |
8.33%
|
|
| Additional Fund Statistics [Text Block] |
Key Fund Statistics
The following table outlines key fund statistics as of the fiscal six-month period ended April 30, 2026.
| Fund net assets |
$71,328,354 |
| Total number of portfolio holdings1 |
106 |
| Portfolio turnover rate |
8.33% |
|
1
|
Number of portfolio holdings is calculated at the issuer level. Excludes Money Market Funds.
|
|
|
| Holdings [Text Block] |
Sector Allocation †
| Communication Services |
0.7% |
| Consumer Discretionary |
6.8% |
| Consumer Staples |
1.5% |
| Financials |
5.9% |
| Health Care |
32.5% |
| Industrials |
28.4% |
| Information Technology |
23.3% |
| Materials |
0.1% |
| Utilities |
0.5% |
| Short-Term Investments and Other Net Assets |
0.3% |
|
100.0% |
|
|
| C000025000 [Member] |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
Alger Small Cap Growth Institutional Fund
|
|
| Class Name |
Class I
|
|
| Trading Symbol |
ALSRX
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about the Alger Small Cap Growth Institutional Fund (“Fund”) for the period from November 1, 2025 to April 30, 2026.
|
|
| Shareholder Report Annual or Semi-Annual |
semi-annual shareholder report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at www.alger.com/fundliterature. You can also request a copy of the semi-annual report by contacting us at (800) 992-3863.
|
|
| Additional Information Phone Number |
(800) 992-3863
|
|
| Additional Information Website |
www.alger.com/fundliterature
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
| Fund (Class/Ticker) |
Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
Alger Small Cap Growth Institutional Fund
(Class I / ALSRX) |
$71 |
1.43%(a) |
|
|
| Expenses Paid, Amount |
$ 71
|
|
| Expense Ratio, Percent |
1.43%
|
[19] |
| Net Assets |
$ 71,328,354
|
|
| Holdings Count | Holding |
106
|
[20] |
| Investment Company Portfolio Turnover |
8.33%
|
|
| Additional Fund Statistics [Text Block] |
Key Fund Statistics
The following table outlines key fund statistics as of the fiscal six-month period ended April 30, 2026.
| Fund net assets |
$71,328,354 |
| Total number of portfolio holdings1 |
106 |
| Portfolio turnover rate |
8.33% |
|
1
|
Number of portfolio holdings is calculated at the issuer level. Excludes Money Market Funds.
|
|
|
| Holdings [Text Block] |
Sector Allocation †
| Communication Services |
0.7% |
| Consumer Discretionary |
6.8% |
| Consumer Staples |
1.5% |
| Financials |
5.9% |
| Health Care |
32.5% |
| Industrials |
28.4% |
| Information Technology |
23.3% |
| Materials |
0.1% |
| Utilities |
0.5% |
| Short-Term Investments and Other Net Assets |
0.3% |
|
100.0% |
|
|
| C000122071 [Member] |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
Alger Focus Equity Fund
|
|
| Class Name |
Class A
|
|
| Trading Symbol |
ALAFX
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about the Alger Focus Equity Fund (“Fund”) for the period from November 1, 2025 to April 30, 2026.
|
|
| Shareholder Report Annual or Semi-Annual |
semi-annual shareholder report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at www.alger.com/fundliterature. You can also request a copy of the semi-annual report by contacting us at (800) 992-3863.
|
|
| Additional Information Phone Number |
(800) 992-3863
|
|
| Additional Information Website |
www.alger.com/fundliterature
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
| Fund (Class/Ticker) |
Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
Alger Focus Equity Fund
(Class A / ALAFX) |
$46 |
0.91%(a) |
|
|
| Expenses Paid, Amount |
$ 46
|
|
| Expense Ratio, Percent |
0.91%
|
[21] |
| Net Assets |
$ 6,123,571,016
|
|
| Holdings Count | Holding |
50
|
[22] |
| Investment Company Portfolio Turnover |
52.02%
|
|
| Additional Fund Statistics [Text Block] |
Key Fund Statistics
The following table outlines key fund statistics as of the fiscal six-month period ended April 30, 2026.
| Fund net assets |
$6,123,571,016 |
| Total number of portfolio holdings1 |
50 |
| Portfolio turnover rate |
52.02% |
|
1
|
Number of portfolio holdings is calculated at the issuer level. Excludes Money Market Funds.
|
|
|
| Holdings [Text Block] |
Sector Allocation †
| Communication Services |
13.0% |
| Consumer Discretionary |
13.3% |
| Financials |
1.4% |
| Health Care |
5.7% |
| Industrials |
6.5% |
| Information Technology |
55.7% |
| Materials |
0.3% |
| Utilities |
2.0% |
| Short-Term Investments and Other Net Assets |
2.1% |
|
100.0% |
|
|
| C000122072 [Member] |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
Alger Focus Equity Fund
|
|
| Class Name |
Class C
|
|
| Trading Symbol |
ALCFX
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about the Alger Focus Equity Fund (“Fund”) for the period from November 1, 2025 to April 30, 2026.
|
|
| Shareholder Report Annual or Semi-Annual |
semi-annual shareholder report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at www.alger.com/fundliterature. You can also request a copy of the semi-annual report by contacting us at (800) 992-3863.
|
|
| Additional Information Phone Number |
(800) 992-3863
|
|
| Additional Information Website |
www.alger.com/fundliterature
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
| Fund (Class/Ticker) |
Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
Alger Focus Equity Fund
(Class C / ALCFX) |
$84 |
1.68%(a) |
|
|
| Expenses Paid, Amount |
$ 84
|
|
| Expense Ratio, Percent |
1.68%
|
[23] |
| Net Assets |
$ 6,123,571,016
|
|
| Holdings Count | Holding |
50
|
[24] |
| Investment Company Portfolio Turnover |
52.02%
|
|
| Additional Fund Statistics [Text Block] |
Key Fund Statistics
The following table outlines key fund statistics as of the fiscal six-month period ended April 30, 2026.
| Fund net assets |
$6,123,571,016 |
| Total number of portfolio holdings1 |
50 |
| Portfolio turnover rate |
52.02% |
|
1
|
Number of portfolio holdings is calculated at the issuer level. Excludes Money Market Funds.
|
|
|
| Holdings [Text Block] |
Sector Allocation †
| Communication Services |
13.0% |
| Consumer Discretionary |
13.3% |
| Financials |
1.4% |
| Health Care |
5.7% |
| Industrials |
6.5% |
| Information Technology |
55.7% |
| Materials |
0.3% |
| Utilities |
2.0% |
| Short-Term Investments and Other Net Assets |
2.1% |
|
100.0% |
|
|
| C000024998 [Member] |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
Alger Focus Equity Fund
|
|
| Class Name |
Class I
|
|
| Trading Symbol |
ALGRX
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about the Alger Focus Equity Fund (“Fund”) for the period from November 1, 2025 to April 30, 2026.
|
|
| Shareholder Report Annual or Semi-Annual |
semi-annual shareholder report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at www.alger.com/fundliterature. You can also request a copy of the semi-annual report by contacting us at (800) 992-3863.
|
|
| Additional Information Phone Number |
(800) 992-3863
|
|
| Additional Information Website |
www.alger.com/fundliterature
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
| Fund (Class/Ticker) |
Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
Alger Focus Equity Fund
(Class I / ALGRX) |
$45 |
0.89%(a) |
|
|
| Expenses Paid, Amount |
$ 45
|
|
| Expense Ratio, Percent |
0.89%
|
[25] |
| Net Assets |
$ 6,123,571,016
|
|
| Holdings Count | Holding |
50
|
[26] |
| Investment Company Portfolio Turnover |
52.02%
|
|
| Additional Fund Statistics [Text Block] |
Key Fund Statistics
The following table outlines key fund statistics as of the fiscal six-month period ended April 30, 2026.
| Fund net assets |
$6,123,571,016 |
| Total number of portfolio holdings1 |
50 |
| Portfolio turnover rate |
52.02% |
|
1
|
Number of portfolio holdings is calculated at the issuer level. Excludes Money Market Funds.
|
|
|
| Holdings [Text Block] |
Sector Allocation †
| Communication Services |
13.0% |
| Consumer Discretionary |
13.3% |
| Financials |
1.4% |
| Health Care |
5.7% |
| Industrials |
6.5% |
| Information Technology |
55.7% |
| Materials |
0.3% |
| Utilities |
2.0% |
| Short-Term Investments and Other Net Assets |
2.1% |
|
100.0% |
|
|
| C000179522 [Member] |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
Alger Focus Equity Fund
|
|
| Class Name |
Class Y
|
|
| Trading Symbol |
ALGYX
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about the Alger Focus Equity Fund (“Fund”) for the period from November 1, 2025 to April 30, 2026.
|
|
| Shareholder Report Annual or Semi-Annual |
semi-annual shareholder report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at www.alger.com/fundliterature. You can also request a copy of the semi-annual report by contacting us at (800) 992-3863.
|
|
| Additional Information Phone Number |
(800) 992-3863
|
|
| Additional Information Website |
www.alger.com/fundliterature
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
| Fund (Class/Ticker) |
Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
Alger Focus Equity Fund
(Class Y / ALGYX) |
$30 |
0.60%(a) |
|
|
| Expenses Paid, Amount |
$ 30
|
|
| Expense Ratio, Percent |
0.60%
|
[27] |
| Net Assets |
$ 6,123,571,016
|
|
| Holdings Count | Holding |
50
|
[28] |
| Investment Company Portfolio Turnover |
52.02%
|
|
| Additional Fund Statistics [Text Block] |
Key Fund Statistics
The following table outlines key fund statistics as of the fiscal six-month period ended April 30, 2026.
| Fund net assets |
$6,123,571,016 |
| Total number of portfolio holdings1 |
50 |
| Portfolio turnover rate |
52.02% |
|
1
|
Number of portfolio holdings is calculated at the issuer level. Excludes Money Market Funds.
|
|
|
| Holdings [Text Block] |
Sector Allocation †
| Communication Services |
13.0% |
| Consumer Discretionary |
13.3% |
| Financials |
1.4% |
| Health Care |
5.7% |
| Industrials |
6.5% |
| Information Technology |
55.7% |
| Materials |
0.3% |
| Utilities |
2.0% |
| Short-Term Investments and Other Net Assets |
2.1% |
|
100.0% |
|
|
| C000122073 [Member] |
|
|
| Shareholder Report [Line Items] |
|
|
| Fund Name |
Alger Focus Equity Fund
|
|
| Class Name |
Class Z
|
|
| Trading Symbol |
ALZFX
|
|
| Annual or Semi-Annual Statement [Text Block] |
This semi-annual shareholder report contains important information about the Alger Focus Equity Fund (“Fund”) for the period from November 1, 2025 to April 30, 2026.
|
|
| Shareholder Report Annual or Semi-Annual |
semi-annual shareholder report
|
|
| Additional Information [Text Block] |
You can find additional information about the Fund at www.alger.com/fundliterature. You can also request a copy of the semi-annual report by contacting us at (800) 992-3863.
|
|
| Additional Information Phone Number |
(800) 992-3863
|
|
| Additional Information Website |
www.alger.com/fundliterature
|
|
| Expenses [Text Block] |
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
| Fund (Class/Ticker) |
Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
Alger Focus Equity Fund
(Class Z / ALZFX) |
$31 |
0.62%(a) |
|
|
| Expenses Paid, Amount |
$ 31
|
|
| Expense Ratio, Percent |
0.62%
|
[29] |
| Net Assets |
$ 6,123,571,016
|
|
| Holdings Count | Holding |
50
|
[30] |
| Investment Company Portfolio Turnover |
52.02%
|
|
| Additional Fund Statistics [Text Block] |
Key Fund Statistics
The following table outlines key fund statistics as of the fiscal six-month period ended April 30, 2026.
| Fund net assets |
$6,123,571,016 |
| Total number of portfolio holdings1 |
50 |
| Portfolio turnover rate |
52.02% |
|
1
|
Number of portfolio holdings is calculated at the issuer level. Excludes Money Market Funds.
|
|
|
| Holdings [Text Block] |
Sector Allocation †
| Communication Services |
13.0% |
| Consumer Discretionary |
13.3% |
| Financials |
1.4% |
| Health Care |
5.7% |
| Industrials |
6.5% |
| Information Technology |
55.7% |
| Materials |
0.3% |
| Utilities |
2.0% |
| Short-Term Investments and Other Net Assets |
2.1% |
|
100.0% |
|
|
|
|