Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 263,621	$ 208,057	$ 778,603	$ 575,067
Other comprehensive (loss) income:
Foreign currency translation adjustments, before tax	(9,573)	16,440	(14,623)	1,361
Income tax benefit (expense)	224	(98)	272	42
Foreign currency translation adjustments, net of tax	(9,349)	16,342	(14,351)	1,403
Changes in employee benefit related items:
Amortization of prior service cost	6	6	18	18
Recognized actuarial gain	324	325	729	975
Changes in employee benefit related items	330	331	747	993
Income tax (expense)	(2)	(2)	(4)	(80)
Employee benefit related items, net of tax	328	329	743	913
Other comprehensive (loss) income	(9,021)	16,671	(13,608)	2,316
Less: Comprehensive (loss) income in consolidated entities attributable to non-controlling interests	(1,074)	81	2,207	(4,550)
Comprehensive income attributable to AB Unitholders	$ 255,674	$ 224,647	$ 762,788	$ 581,933