Investments Marketable Equity Securities Gains (Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Marketable Equity Securities Gains (Losses) [Abstract]
Marketable equity securities gains (losses), net	$ 3,350	$ (2,701)	$ 31,015	$ 10,461
Less net gains recognized on marketable equity securities sold	0	2,568	263	39,884
Unrealized gains (losses) recognized on marketable equity securities held	$ 3,350	$ (5,269)	$ 30,752	$ (29,423)