Core Bond Class [Member] Expense Example - Core Bond Class - AB Core Bond Portfolio - Core Bond Class	Sep. 30, 2025 USD ($)
Prospectus [Line Items]
Expense Example, with Redemption, 1 Year	$ 29
Expense Example, with Redemption, 3 Years	119
Expense Example, with Redemption, 5 Years	217
Expense Example, with Redemption, 10 Years	$ 505

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