Investments (Unrealized Gains (Losses) on Equity Securities) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Gain (Loss) on Securities [Line Items]
Unrealized gains (losses) recognized in income on equity securities on securities remaining in our portfolio at September 30, 2020	$ 4,338	$ 1,109	$ (7,101)	$ 1,805
Unrealized gains (losses) recognized in income on equity securities on securities sold in each respective period	0	(21,426)	3	(9,896)
Total unrealized gains (losses) recognized in income on equity securities	$ 4,338	$ (20,317)	$ (7,098)	$ (8,091)