Consolidated Company-Sponsored Investment Funds - Summary of Balance Sheet Amounts (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025
Condensed Balance Sheet Statements, Captions [Line Items]
Total assets	$ 9,206,393	$ 9,277,776
Liabilities	4,136,143	4,262,658
Redeemable non-controlling interest	255,651	178,967
Partners' capital attributable to AB Unitholders	4,814,599	4,836,151	$ 4,767,952
Total liabilities, non-controlling interest and capital	9,206,393	9,277,776
Company-Sponsored Investment Funds
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	20,269	17,726
Investments	399,525	330,534
Other assets	28,674	25,120
Total assets	448,468	373,380
Liabilities	33,449	25,281
Redeemable non-controlling interest	255,651	178,967
Partners' capital attributable to AB Unitholders	159,368	169,132
Total liabilities, non-controlling interest and capital	448,468	373,380
VIEs
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	20,007	17,617
Investments	373,576	304,035
Other assets	28,374	24,778
Total assets	421,957	346,430
Liabilities	33,369	25,132
Redeemable non-controlling interest	245,937	169,091
Partners' capital attributable to AB Unitholders	142,651	152,207
Total liabilities, non-controlling interest and capital	421,957	346,430
VOEs
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	262	109
Investments	25,949	26,499
Other assets	300	342
Total assets	26,511	26,950
Liabilities	80	149
Redeemable non-controlling interest	9,714	9,876
Partners' capital attributable to AB Unitholders	16,717	16,925
Total liabilities, non-controlling interest and capital	$ 26,511	$ 26,950