Investment In Unconsolidated Affiliate (Condensed Statement Of Operations Of LSV) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Investments in and Advances to Affiliates [Line Items]
Revenues	$ 241,237	$ 237,760	$ 479,135	$ 470,253
Net income	49,555	53,603	99,520	111,331
LSV [Member]
Investments in and Advances to Affiliates [Line Items]
Revenues	69,189	81,748	146,654	161,150
Net income	$ 57,372	$ 72,018	$ 124,045	$ 141,964