Investment in AB (Details) - USD ($) $ in Thousands	3 Months Ended														12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	[1]	Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2015	[1]	Jun. 30, 2015	[1]	Mar. 31, 2015		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in Equity Method Investment
Investment in AB as of January 1,					$ 1,576,120								$ 1,616,309		$ 1,576,120	$ 1,616,309
Equity in net income attributable to AB Unitholders	$ 78,630	$ 55,925	$ 44,657		$ 60,177	[1]	$ 56,890	[1]	$ 48,387		$ 53,799		$ 51,008	[1]	239,389	210,084	$ 200,931
Changes in accumulated other comprehensive loss															(7,342)	(5,514)	(16,635)
Cash distributions received from AB															(191,989)	(217,065)	(203,919)
Additional investments with proceeds from exercises of compensatory options to buy AB Holding Units, net															6,108	9,233	18,955
Capital contributions to (from) AB															(200)	490	(1,814)
AB Holding Units retired															(184,336)	(155,073)	(14,577)
AB Holding Units issued to fund long-term incentive compensation plans															103,820	115,045	108,034
Change in AB Holding Units held by AB for long-term incentive compensation plans															(1,062)	2,611
Investment in AB as of December 31,	$ 1,540,508						$ 1,576,120								$ 1,540,508	$ 1,576,120	$ 1,616,309

[1] Certain prior-period amounts have been revised, see Note 2 for a discussion of the revision.