Investments Investments (Equity Method Investments, Statement of Financial Position) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Investments [Abstract]
Total assets	$ 26,017,399	$ 3,946,992
Total liabilities	164,080	65,903
Partners' capital	25,853,319	3,881,089
Total liabilities and partners’ capital	26,017,399	3,946,992
Total liabilities and partners’ capital included above	325,677	269,775
Equity in LP/LLC interests not included above	114,505	83,029
Carrying value	$ 440,182	$ 352,804