Investment In Unconsolidated Affiliate (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Investments in and Advances to Affiliates [Line Items]
Distributions received from unconsolidated affiliate			$ 89,362	$ 75,142
Company's share in the earnings of equity method investee	$ 41,073	$ 36,315	$ 81,680	69,880
LSV Asset Management
Investments in and Advances to Affiliates [Line Items]
Equity method investment, ownership percentage	38.90%		38.90%
Total investment in equity method investee	$ 51,810		$ 51,810
Distributions received from unconsolidated affiliate			89,362	75,142
Company's share in the earnings of equity method investee	$ 41,073	$ 36,315	$ 81,680	$ 69,880

Amount of distribution received from equity method investee for return on investment, classified as operating activities. Excludes distribution for return of investment, classified as investing activities.

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