Consolidated Sponsored Investment Products - Schedule of Trading Securities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost	$ 133,856	$ 41,367
Unrealized Loss	(2,979)	(165)
Unrealized Gain	8,177	2,025
Fair Value	139,054	43,227
Trading Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost	48,994	24,830
Unrealized Loss	(2,097)	(21)
Unrealized Gain	217	1,003
Fair Value	47,114	25,812
Trading Equity Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost	84,862	16,537
Unrealized Loss	(882)	(144)
Unrealized Gain	7,960	1,022
Fair Value	$ 91,940	$ 17,415