Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Statement of Comprehensive Income [Abstract]
Net income	$ 308,636	$ 221,694
Other comprehensive (loss) income:
Foreign currency translation adjustments, before tax	(6,209)	10,749
Income tax (expense) benefit	(48)	55
Foreign currency translation adjustments, net of tax	(6,257)	10,804
Changes in employee benefit related items:
Amortization of prior service cost	0	611
Less: reclassification adjustment for (losses) included in net income upon retirement plan liquidation	0	(22,898)
Changes in employee benefit related items	0	23,509
Income tax (expense)	0	(147)
Employee benefit related items, net of tax	0	23,362
Other comprehensive (loss) income	(6,257)	34,166
Less: Comprehensive income in consolidated entities attributable to non-controlling interests	13,151	895
Comprehensive income attributable to AB Unitholders	$ 289,228	$ 254,965