Marketable Investment Securities, Restricted Cash and Cash Equivalents, and Other Investment Securities - Gains And Losses On Sales And Changes In Carrying Amounts Of Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Marketable Investment Securities, Restricted Cash and Cash Equivalents, and Other Investment Securities
Marketable investment securities - realized and unrealized gains (losses)		$ 3,119	$ 5,313
Costs related to early redemption of debt			(3,261)
Gain (loss) on sale of subsidiary			7,004
Equity in earnings (losses) of affiliates	$ 653	3,514	(2,110)
Other	1,033	976	2,048
Total	$ 1,686	$ 7,609	$ 8,994