Investments Investments (Equity Method Investments, Statement of Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments [Abstract]
Total revenue	$ 819,904	$ 128,356	$ 319,414
Total expenses	(200,666)	(39,040)	(31,680)
Net earnings (losses)	619,238	89,316	287,734
Earnings in net earnings (losses) included above	24,971	(2,470)	12,439
Equity in net earnings (losses) of LP/LLC interests not included above	5,077	(1,452)	5,191
Total equity in net earnings (losses)	$ 30,048	$ (3,922)	$ 17,630