Investment In Unconsolidated Affiliate (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Apr. 01, 2020	Mar. 31, 2020
Investments in and Advances to Affiliates [Line Items]
Distributions received from unconsolidated affiliate			$ 119,821	$ 123,663
Company's share in the earnings of equity method investee	$ 28,305	$ 37,609	86,488	112,758
LSV Asset Management
Investments in and Advances to Affiliates [Line Items]
Equity method investment, ownership percentage					38.80%	38.90%
Total investment in equity method investee	33,117		33,117
Distributions received from unconsolidated affiliate			119,821	123,663
Company's share in the earnings of equity method investee	$ 28,305	$ 37,609	$ 86,488	$ 112,758