Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 174,009	$ 181,926	$ 333,239	$ 388,772
Other comprehensive income (loss):
Foreign currency translation adjustment, before reclassification and tax	(2,178)	(20,656)	452	(10,735)
Less: reclassification adjustment for (losses) included in net income upon liquidation	0	(100)	0	(100)
Foreign currency translation adjustments, before tax	(2,178)	(20,556)	452	(10,635)
Income tax expense	(73)	0	(150)	0
Foreign currency translation adjustments, net of tax	(2,251)	(20,556)	302	(10,635)
Changes in employee benefit related items:
Amortization of prior service cost	6	5	12	11
Recognized actuarial gain	285	286	552	568
Changes in employee benefit related items	291	291	564	579
Income tax benefit (expense)	25	2	35	(116)
Employee benefit related items, net of tax	316	293	599	463
Other	0	374	0	374
Other comprehensive (loss) income	(1,935)	(19,889)	901	(9,798)
Less: Comprehensive income in consolidated entities attributable to non-controlling interests	7,774	220	17,870	22,887
Comprehensive income attributable to AB Unitholders	$ 164,300	$ 161,817	$ 316,270	$ 356,087