Consolidated Statement of Stockholders’ Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income(Loss)	Total
Balance at the beginning of the period at Dec. 31, 2014					$ (50,443)
Increase (Decrease) in Stockholders' Equity
Net income						$ 134,558
Other comprehensive income					(1,288)
Balance at the end of the period at Jun. 30, 2015					(51,731)
Balance at the beginning of the period at Mar. 31, 2015					(47,690)
Increase (Decrease) in Stockholders' Equity
Net income						67,445
Other comprehensive income					(4,041)
Balance at the end of the period at Jun. 30, 2015					(51,731)
Balance at the beginning of the period at Dec. 31, 2015	$ 997	$ 331,611	$ 1,141,608	$ (566,256)	(61,505)	846,455
Balance (in shares) at Dec. 31, 2015	99,701
Increase (Decrease) in Stockholders' Equity
Net income			70,663			70,663
Recognition of equity compensation		26,147				26,147
Net issuance/forfeiture of nonvested shares		(72,935)		72,935
Dividends accrued, $0.92 per share			(76,625)			(76,625)
Tax impact of share-based payment arrangements		(5,617)				(5,617)
Repurchase of common stock				(47,461)		(47,461)
Other comprehensive income					3,997	3,997
Balance at the end of the period at Jun. 30, 2016	$ 997	279,206	1,135,646	(540,782)	(57,508)	817,559
Balance (in shares) at Jun. 30, 2016	99,701
Increase (Decrease) in Redeemable Noncontrolling Interest
Adoption of consolidation guidance on January 1, 2016 - redeemable noncontrolling interests in sponsored funds						14,330
Net income						377
Net redemption of redeemable noncontrolling interests in sponsored funds						(3,842)
Balance at the end of the period at Jun. 30, 2016						10,865
Balance at the beginning of the period at Mar. 31, 2016					(60,352)
Increase (Decrease) in Stockholders' Equity
Net income						33,695
Other comprehensive income					2,844
Balance at the end of the period at Jun. 30, 2016	$ 997	$ 279,206	$ 1,135,646	$ (540,782)	$ (57,508)	817,559
Balance (in shares) at Jun. 30, 2016	99,701
Balance at the end of the period at Jun. 30, 2016						$ 10,865