Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 694,846	$ 586,302	$ 564,317
Other comprehensive (loss) income:
Foreign currency translation adjustments, before reclassification and tax:	(19,849)	(15,396)	(20,872)
Less: reclassification adjustment for (losses) gains included in net income upon liquidation	(6)	1,542	0
Foreign currency translation adjustments, before tax	(19,843)	(16,938)	(20,872)
Income tax benefit	0	0	0
Foreign currency translation adjustments, net of tax	(19,843)	(16,938)	(20,872)
Unrealized gains (losses) on investments:
Unrealized gains (losses) arising during period	10	(357)	1,649
Less: reclassification adjustment for (losses) gains included in net income	(6)	1,256	19
Changes in unrealized gains (losses) on investments	16	(1,613)	1,630
Income tax (expense) benefit	(7)	701	(766)
Unrealized gains (losses on investments, net of tax	9	(912)	864
Changes in employee benefit related items:
Amortization of prior service cost	93	(895)	(5,197)
Recognized actuarial (loss) gain	(3,043)	3,267	(19,656)
Changes in employee benefit related items	(2,950)	2,372	(24,853)
Income tax (expense) benefit	(22)	(165)	298
Employee benefit related items, net of tax	(2,972)	2,207	(24,555)
Other comprehensive (loss)	(22,806)	(15,643)	(44,563)
Less: Comprehensive income in consolidated entities attributable to non-controlling interests	21,426	6,242	355
Comprehensive income attributable to AB Unitholders	$ 650,614	$ 564,417	$ 519,399