Condensed Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 155,769	$ 136,432	$ 298,513	$ 254,970
Other comprehensive income (loss):
Foreign currency translation adjustment, before reclassification and tax:	7,598	3,950	(4,677)	6,099
Less: reclassification adjustment for gains included in net income upon liquidation	1,542	0	1,542	0
Foreign currency translation adjustments, before tax	6,056	3,950	(6,219)	6,099
Income tax expense	0	0	0	0
Foreign currency translation adjustments, net of tax	6,056	3,950	(6,219)	6,099
Unrealized (losses) gains on investments:
Unrealized (losses) gains arising during period	(530)	414	(341)	842
Less: reclassification adjustment for gains (losses) included in net income	0	1	0	(3)
Change in unrealized (losses) gains on investments	(530)	413	(341)	845
Income tax benefit (expense)	161	(143)	280	(286)
Unrealized (losses) gains on investments, net of tax	(369)	270	(61)	559
Changes in employee benefit related items:
Amortization of prior service cost	0	(1,300)	0	(2,599)
Recognized actuarial gain	238	488	475	974
Changes in employee benefit related items	238	(812)	475	(1,625)
Income tax (expense) benefit	(3)	10	(65)	(10)
Employee benefit related items, net of tax	(235)	802	(410)	1,635
Other comprehensive income (loss)	5,922	3,418	(5,870)	5,023
Less: Comprehensive income (loss) in consolidated entities attributable to non-controlling interests	6,683	(12)	7,891	1,842
Comprehensive income attributable to AB Unitholders	$ 155,008	$ 139,862	$ 284,752	$ 258,151