Condensed Consolidated Statements of Comprehensive Income (unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Condensed Consolidated Statements of Comprehensive Income (unaudited) [Abstract]
Net income	$ 142,744	$ 118,538
Other comprehensive income (loss):
Foreign currency translation adjustments	(12,275)	2,149
Income tax expense	0	0
Foreign currency translation adjustments, net of tax	(12,275)	2,149
Unrealized gains on investments:
Unrealized gains arising during period	189	428
Less: reclassification adjustment for (losses) included in net income	0	(4)
Change in unrealized gains on investments	189	432
Income tax benefit (expense)	119	(143)
Unrealized gains on investments, net of tax	308	289
Changes in employee benefit related items:
Amortization of prior service cost	0	(1,299)
Recognized actuarial gain	237	486
Changes in employee benefit related items	237	(813)
Income tax expense	(62)	(20)
Employee benefit related items, net of tax	175	(833)
Other comprehensive (loss) income	(11,792)	1,605
Less: Comprehensive income in consolidated entities attributable to non-controlling interests	1,208	1,854
Comprehensive income attributable to AB Unitholders	$ 129,744	$ 118,289