Investment in AllianceBernstein (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Investment in AllianceBernstein [Abstract]
Investment in AllianceBernstein				$ 1,786,291				$ 1,800,065	$ 1,786,291	$ 1,800,065
Equity in net (loss) income attributable to AllianceBernstein Unitholders	(193,458)	34,074	42,745	51,058	50,168	18,914	38,925	54,210	(65,581)	162,217	192,513
Additional investments with proceeds from exercises of compensatory options to buy Holding Units, net									1,478	8,287	0
Changes in accumulated other comprehensive income (loss)									(2,549)	(3,912)	16,479
Cash distributions received from AllianceBernstein									(178,757)	(182,410)	(160,114)
Issuance of Holding Units to AllianceBernstein to fund deferred compensation plan awards									0	78,545	272,167
Change in Holding Units held by AllianceBernstein for deferred compensation plans									79,098	(76,501)
Investment in AllianceBernstein	$ 1,619,980				$ 1,786,291				$ 1,619,980	$ 1,786,291	$ 1,800,065