Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 157,480	$ 173,731	$ 466,007	$ 463,611
Other comprehensive income (loss):
Foreign currency translation adjustment, before reclassification and tax	7,735	437	24,091	539
Less: reclassification adjustment for (losses) included in net income upon liquidation	0	(6)	0	(6)
Foreign currency translation adjustments, before tax	7,735	443	24,091	545
Income tax benefit	0	0	0	0
Foreign currency translation adjustments, net of tax	7,735	443	24,091	545
Unrealized (losses) gains on investments:
Unrealized (losses) gains arising during period	(4)	12	6	(7)
Less: reclassification adjustment for (losses) included in net income	0	(7)	0	(10)
Change in unrealized (losses) gains on investments	(4)	19	6	3
Income tax benefit (expense)	5	(8)	3	(5)
Unrealized gains (losses) on investments, net of tax	1	11	9	(2)
Changes in employee benefit related items:
Amortization of prior service cost	6	6	18	87
Recognized actuarial loss	295	244	818	202
Changes in employee benefit related items	301	250	836	289
Income tax (expense) benefit	(2)	24	(81)	(51)
Employee benefit related items, net of tax	299	274	755	238
Other comprehensive income	8,035	728	24,855	781
Less: Comprehensive income in consolidated entities attributable to non-controlling interests	16,554	15,725	50,990	14,815
Comprehensive income attributable to AB Unitholders	$ 148,961	$ 158,734	$ 439,872	$ 449,577