Investment Funds (Schedule of Investment Funds) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Maximum loss exposure	$ 621,000
Investment funds	1,480,612	$ 1,309,430
Income (Losses)	220,014	54,253	$ 69,194
Ceded to Other Companies	1,837,267	1,585,210	1,398,719
Deferred compensation trust assets	$ 34,000	0
Lifson Re
Schedule of Equity Method Investments [Line Items]
Percentage of reinsurance placements of share placed amounts	22.50%
Ceded to Other Companies	$ 245,000
Financial services
Schedule of Equity Method Investments [Line Items]
Investment funds	431,818	434,437
Income (Losses)	98,893	34,763	29,005
Real estate
Schedule of Equity Method Investments [Line Items]
Investment funds	273,690	310,783
Income (Losses)	29,484	7,543	19,154
Energy
Schedule of Equity Method Investments [Line Items]
Investment funds	150,224	140,935
Income (Losses)	22,118	(11,039)	(18,136)
Transportation
Schedule of Equity Method Investments [Line Items]
Investment funds	336,688	190,125
Income (Losses)	42,424	(616)	14,193
Other funds
Schedule of Equity Method Investments [Line Items]
Investment funds	288,192	233,150
Income (Losses)	$ 27,095	$ 23,602	$ 24,978

Amount of written premiums ceded to other entities.

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