Investments - Equity Method Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Remaining unfunded commitments on equity method investments	$ 60,104	$ 63,313
Carrying Value	$ 40,183	$ 39,886
% of Total	100.00%	100.00%
Hedge fund investments
Schedule of Equity Method Investments [Line Items]
Carrying Value	$ 31,125	$ 29,435
% of Total	77.50%	73.80%
Investment in limited partnerships
Schedule of Equity Method Investments [Line Items]
Remaining unfunded commitments on equity method investments	$ 342	$ 326
Carrying Value	$ 9,058	$ 10,451
% of Total	22.50%	26.20%