Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 271,143	$ 198,261	$ 514,982	$ 367,010
Other comprehensive income (loss):
Foreign currency translation adjustments, before tax	2,088	6,317	(5,050)	(15,079)
Income tax benefit	26	67	48	140
Foreign currency translation adjustments, net of tax	2,114	6,384	(5,002)	(14,939)
Changes in employee benefit related items:
Amortization of prior service cost	6	6	12	12
Recognized actuarial gain	324	325	405	650
Changes in employee benefit related items	330	331	417	662
Income tax (expense)	(2)	(1)	(2)	(78)
Employee benefit related items, net of tax	328	330	415	584
Other comprehensive income (loss)	2,442	6,714	(4,587)	(14,355)
Less: Comprehensive income (loss) in consolidated entities attributable to non-controlling interests	3,573	20,940	3,281	(4,631)
Comprehensive income attributable to AB Unitholders	$ 270,012	$ 184,035	$ 507,114	$ 357,286