Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 198,261	$ 174,009	$ 367,010	$ 333,239
Other comprehensive income (loss):
Foreign currency translation adjustments, before tax	6,317	(2,178)	(15,079)	452
Income tax benefit (expense)	67	(73)	140	(150)
Foreign currency translation adjustments, net of tax	6,384	(2,251)	(14,939)	302
Changes in employee benefit related items:
Amortization of prior service cost	6	6	12	12
Recognized actuarial gain	325	285	650	552
Changes in employee benefit related items	331	291	662	564
Income tax (expense) benefit	(1)	25	(78)	35
Employee benefit related items, net of tax	330	316	584	599
Other comprehensive income (loss)	6,714	(1,935)	(14,355)	901
Less: Comprehensive income (loss) in consolidated entities attributable to non-controlling interests	20,940	7,774	(4,631)	17,870
Comprehensive income attributable to AB Unitholders	$ 184,035	$ 164,300	$ 357,286	$ 316,270