Investment In Unconsolidated Affiliate (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Apr. 01, 2021
Investments in and Advances to Affiliates [Line Items]
Distributions received from unconsolidated affiliate	$ 28,774	$ 40,226
Company's share in the earnings of equity method investee	$ 33,350	29,907
LSV Asset Management
Investments in and Advances to Affiliates [Line Items]
Equity method investment, ownership percentage	38.80%
Total investment in equity method investee	$ 51,743
Distributions received from unconsolidated affiliate	28,774	40,226
Company's share in the earnings of equity method investee	$ 33,350	$ 29,907
LSV Asset Management \| Subsequent Event
Investments in and Advances to Affiliates [Line Items]
Equity method investment, ownership percentage			38.70%

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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