Equity and Debt Investments - Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Equity Investments
Equity method investments	$ 1,886,324	$ 1,987,515
Total equity investments	2,121,263	2,256,214
Debt Securities
Total debt securities	56,698	57,591
Equity and debt investments	2,177,961	2,313,805
Investment ventures
Equity Investments
Equity method investments	1,703,174	1,845,129
Investment ventures and Private funds and non-traded REIT	91,147	91,472
Private funds
Equity Investments
Equity method investments	183,150	142,386
Investment ventures and Private funds and non-traded REIT	41,393	38,641
N-Star CDO bonds
Debt Securities
N-Star CDO bonds, available for sale	54,474	54,859
CMBS of consolidated fund
Debt Securities
CMBS of consolidated fund, at fair value	2,224	2,732
Level 1 \| Marketable equity securities
Equity Investments
Marketable equity securities	$ 102,399	$ 138,586

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