Investments (Gain (Loss) on Marketable Equity Securities) (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Investments [Abstract]
Gain (loss) on marketable equity securities, net	$ 59,364	$ 17,404	$ (1,139)	$ 49,261
Less: Net losses (gains) in earnings from marketable equity securities sold and donated	0	61	13,382	(2,919)
Net unrealized gains in earnings from marketable equity securities still held at the end of the period	$ 59,364	$ 17,465	$ 12,243	$ 46,342