Basis of Presentation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	May 28, 2020	Apr. 30, 2020	Sep. 30, 2020	Dec. 31, 2019	Jan. 01, 2019
Basis of Presentation [Line Items]
Cash and cash equivalents			$ 83,386	$ 259,067
Restricted Cash, Current			304	0
Restricted cash			0	304
Operating lease liability			513
Operating lease right of use asset			508	988	$ 300
Dividends payable, date declared		Apr. 30, 2020
Common stock, dividends, per share		$ 5.50
Dividends, cash	$ 170,100
Dividends payable, date paid		May 28, 2020
Dividends payable, date of record		May 14, 2020
Accounting Standards Update 2016-02 [Member] | Restatement Adjustment [Member]
Basis of Presentation [Line Items]
Operating lease liability					300
Operating lease right of use asset					$ 300
Equity Method Investee [Member]
Basis of Presentation [Line Items]
Investments in affiliates, guarantee or other funding obligations			$ 0	$ 0