Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 159,230	$ 206,846
Other comprehensive income (loss):
Foreign currency translation adjustments, before tax	2,630	9,921
Income tax expense	(77)	0
Foreign currency translation adjustments, net of tax	2,553	9,921
Changes in employee benefit related items:
Amortization of prior service cost	6	6
Recognized actuarial gain	267	282
Changes in employee benefit related items	273	288
Income tax benefit (expense)	10	(118)
Employee benefit related items, net of tax	283	170
Other comprehensive income	2,836	10,091
Less: Comprehensive income in consolidated entities attributable to non-controlling interests	10,096	22,667
Comprehensive income attributable to AB Unitholders	$ 151,970	$ 194,270