Investment Information - Equity method investments (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	$ 2,539,124	$ 2,047,889
Credit related funds
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	883,279	740,060
Equity securities
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	403,003	343,058
Real estate
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	323,566	258,518
Lending
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	295,228	179,629
Private equity
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	305,662	235,289
Infrastructure
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	210,174	175,882
Energy
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	$ 118,212	$ 115,453