Investments (Gain (Loss) on Marketable Equity Securities) (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Investments [Abstract]
Gain (loss) on marketable equity securities, net	$ 39,890	$ 7,791	$ (60,503)	$ 31,857
Less: Net losses (gains) in earnings from marketable equity securities sold and donated	4,608	2	13,382	(2,980)
Net unrealized gains (losses) in earnings from marketable equity securities still held at the end of the period	$ 44,498	$ 7,793	$ (47,121)	$ 28,877