Investment in Unconsolidated Affiliates (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investments in and Advances to Affiliates [Line Items]
Company's share in the earnings of LSV	$ 117,134	$ 151,891	$ 159,791
Distributions received from LSV	$ 125,534	148,936	166,698
LSV Asset Management
Investments in and Advances to Affiliates [Line Items]
Ownership interest in LSV	38.80%
Total investment in LSV	$ 98,433
Company's share in the earnings of LSV	117,134	151,891	159,791
Distributions received from LSV	$ 125,534	$ 148,936	$ 166,698

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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