S000084745 [Member] Performance Management - AB Mid Cap Value Portfolio |
Jun. 30, 2026 |
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| Prospectus [Line Items] | |||||||
| Bar Chart and Performance Table [Heading] | BAR CHART AND PERFORMANCE INFORMATION | ||||||
| Performance Narrative [Text Block] |
The bar chart and performance information
provide an indication of the historical risk of an investment in the Fund by showing:
You may obtain updated performance information
on the Fund’s website at www.abfunds.com
(click on “Investments—Mutual Funds”).
The Fund’s past performance before
and after taxes, of course, does not necessarily indicate how it will perform in the future.
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| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance before and after taxes, of course, does not necessarily indicate how it will perform in the future. | ||||||
| Performance Information Illustrates Variability of Returns [Text] | how the Fund’s performance changed from year to year over the life of the Fund; andhow the Fund’s average annual returns for one year and since inception compare to those of a broad-based securities market index and an additional index that more closely reflects the types of securities in which the Fund invests. | ||||||
| Bar Chart Narrative [Text Block] |
The annual returns in the bar chart are
for the Fund’s Class Z shares. Through September 30,
2026, the year‑to‑date
unannualized return for Class Z shares was 14.36%.
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| Bar Chart [Heading] | Bar Chart | ||||||
| Bar Chart Closing [Text Block] | Calendar Year End (%) During the period shown in the bar chart, the Fund’s: Best Quarter was up 4.96%, 3rd quarter, 2025; and Worst Quarter was down -1.24%, 1st quarter, 2025. | ||||||
| Performance Table Heading | Performance Table Average Annual Total Returns (For the periods ended December 31, 2025) | ||||||
| Performance Table Narrative |
After-tax
returns are an estimate, which is based on the highest historical individual federal marginal income tax rates, and do not reflect the
impact of state and local taxes; actual
after-tax returns depend on an individual investor’s tax situation and are likely to differ from those shown, and are not relevant
to investors who hold Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
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| Performance Table Uses Highest Federal Rate | After-tax returns are an estimate, which is based on the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes; | ||||||
| Performance Table Not Relevant to Tax Deferred | actual after-tax returns depend on an individual investor’s tax situation and are likely to differ from those shown, and are not relevant to investors who hold Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. | ||||||
| Performance Availability Website Address [Text] | www.abfunds.com | ||||||
| Class Z | |||||||
| Prospectus [Line Items] | |||||||
| Year to Date Return, Label [Optional Text] | year‑to‑date | ||||||
| Bar Chart, Year to Date Return | 14.36% | ||||||
| Bar Chart, Year to Date Return, Date | Sep. 30, 2026 | ||||||
| Highest Quarterly Return, Label [Optional Text] | Best Quarter | ||||||
| Highest Quarterly Return | 4.96% | ||||||
| Highest Quarterly Return, Date | Sep. 30, 2025 | ||||||
| Lowest Quarterly Return, Label [Optional Text] | Worst Quarter | ||||||
| Lowest Quarterly Return | (1.24%) | ||||||
| Lowest Quarterly Return, Date | Mar. 31, 2025 |