Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 152,272	$ 129,344	$ 308,527	$ 289,880
Other comprehensive income (loss):
Foreign currency translation adjustments, before tax	7,355	(5,123)	16,356	102
Income tax benefit	134	0	0	0
Foreign currency translation adjustments, net of tax	7,489	(5,123)	16,356	102
Unrealized gains (losses) on investments:
Unrealized gains (losses) arising during period	26	(11)	10	(19)
Less: reclassification adjustment for (losses) included in net income	0	0	0	(3)
Change in unrealized gains (losses) on investments	26	(11)	10	(16)
Income tax benefit (expense)	0	4	(2)	3
Unrealized gains (losses) on investments, net of tax	26	(7)	8	(13)
Changes in employee benefit related items:
Amortization of prior service cost	6	10	12	81
Recognized actuarial loss (gain)	264	391	523	(42)
Changes in employee benefit related items	270	401	535	39
Income tax expense	(3)	(4)	(79)	(75)
Employee benefit related items, net of tax	267	397	456	(36)
Other comprehensive income (loss)	7,782	(4,733)	16,820	53
Less: Comprehensive income (loss) in consolidated entities attributable to non-controlling interests	18,042	4,787	34,436	(910)
Comprehensive income attributable to AB Unitholders	$ 142,012	$ 119,824	$ 290,911	$ 290,843