Investment Information - Other investments (Details) - Fair value option - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Schedule Of Other Investments [Line Items]
Other investments	$ 2,122,490	$ 2,429,316
Term loan investments
Schedule Of Other Investments [Line Items]
Other investments	1,109,031	1,326,018
Lending
Schedule Of Other Investments [Line Items]
Other investments	579,320	602,841
Credit related funds
Schedule Of Other Investments [Line Items]
Other investments	92,970	123,020
Energy
Schedule Of Other Investments [Line Items]
Other investments	66,667	97,402
Investment grade fixed income
Schedule Of Other Investments [Line Items]
Other investments	133,936	151,594
Infrastructure
Schedule Of Other Investments [Line Items]
Other investments	48,427	61,786
Private equity
Schedule Of Other Investments [Line Items]
Other investments	72,888	49,376
Real estate
Schedule Of Other Investments [Line Items]
Other investments	$ 19,251	$ 17,279