Consolidated Company-Sponsored Investment Funds - Summary of Balance Sheet Amounts (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025	Jun. 30, 2025
Condensed Balance Sheet Statements, Captions [Line Items]
Total assets	$ 9,241,119	$ 9,277,776
Liabilities	4,213,864	4,262,658
Redeemable non-controlling interest	230,809	178,967
Partners' capital attributable to AB Unitholders	4,796,446	4,836,151	$ 4,733,718
Total liabilities, non-controlling interest and capital	9,241,119	9,277,776
Company-Sponsored Investment Funds
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	5,843	17,726
Investments	431,095	330,534
Other assets	29,618	25,120
Total assets	466,556	373,380
Liabilities	28,510	25,281
Redeemable non-controlling interest	230,809	178,967
Partners' capital attributable to AB Unitholders	207,237	169,132
Total liabilities, non-controlling interest and capital	466,556	373,380
VIEs
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	5,510	17,617
Investments	405,249	304,035
Other assets	29,279	24,778
Total assets	440,038	346,430
Liabilities	28,478	25,132
Redeemable non-controlling interest	221,047	169,091
Partners' capital attributable to AB Unitholders	190,513	152,207
Total liabilities, non-controlling interest and capital	440,038	346,430
VOEs
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	333	109
Investments	25,846	26,499
Other assets	339	342
Total assets	26,518	26,950
Liabilities	32	149
Redeemable non-controlling interest	9,762	9,876
Partners' capital attributable to AB Unitholders	16,724	16,925
Total liabilities, non-controlling interest and capital	$ 26,518	$ 26,950