Investment Funds (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Unfunded commitments	$ 129,000
Investment funds	1,358,997		$ 1,309,430
Income from Investment Funds	38,935	$ 40,577
Written premiums ceded	$ 434,674	385,526
Lifson Re
Schedule of Equity Method Investments [Line Items]
Percentage of reinsurance placements of share placed amounts	22.50%
Written premiums ceded	$ 53,000
Financial services
Schedule of Equity Method Investments [Line Items]
Investment funds	304,461		310,783
Income from Investment Funds	4,434	6,790
Real Estate
Schedule of Equity Method Investments [Line Items]
Investment funds	477,927		434,437
Income from Investment Funds	17,142	15,209
Energy
Schedule of Equity Method Investments [Line Items]
Investment funds	143,852		140,935
Income from Investment Funds	3,320	4,413
Transportation
Schedule of Equity Method Investments [Line Items]
Investment funds	193,401		190,125
Income from Investment Funds	6,228	2,646
Other funds
Schedule of Equity Method Investments [Line Items]
Investment funds	239,356		$ 233,150
Income from Investment Funds	$ 7,811	$ 11,519

Amount of written premiums ceded to other entities.

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