Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 1,153,734	$ 861,783	$ 781,683
Other comprehensive income:
Foreign currency translation adjustments, before reclassification and tax:	(7,839)	23,882	5,986
Less: reclassification adjustment for gains (losses) included in net income upon liquidation	4,458	(216)	0
Foreign currency translation adjustments, before tax	(12,297)	24,098	5,986
Income tax benefit (expense)	457	(854)	(383)
Foreign currency translation adjustments, net of tax	(11,840)	23,244	5,603
Changes in employee benefit related items:
Amortization of prior service cost	24	24	24
Recognized actuarial gain (loss)	15,743	(4,280)	(7,891)
Changes in employee benefit related items	15,767	(4,256)	(7,867)
Income tax (expense) benefit	(59)	(187)	274
Employee benefit related items, net of tax	15,708	(4,443)	(7,593)
Other comprehensive gain (loss)	3,868	18,801	(1,990)
Less: Comprehensive income (loss) in consolidated entities attributable to non-controlling interests	5,111	(4,169)	29,788
Comprehensive income attributable to AB Unitholders	$ 1,152,491	$ 884,753	$ 749,905