Investments - Net Gains (Losses) on Investments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Gain (Loss) on Securities [Line Items]
Net realized gains (losses) on investments sold or redeemed	$ (3,992)	$ 4,266	$ (4,315)	$ 4,084
Change in unrealized gains (losses) on investments sold or redeemed	(28)	(1,883)	(2,198)	(2,080)
Net decrease (increase) in expected credit losses	0	608	0	918
Net unrealized gains (losses) on investments still held	(29,113)	9,919	(46,573)	7,597
Total net gains (losses) on investments	(33,133)	12,910	(53,086)	10,519
Net gains (losses) on other financial instruments	(8,736)	2,751	(18,240)	(39)
Net gains (losses) on investments and other financial instruments	(41,869)	15,661	(71,326)	10,480
Fixed-maturities available for sale
Gain (Loss) on Securities [Line Items]
Gross realized gains	713	9,597	2,143	13,714
Gross realized losses	(4,653)	(7,221)	(8,061)	(12,128)
Fixed-maturities available for sale, net	(3,940)	2,376	(5,918)	1,586
Trading securities
Gain (Loss) on Securities [Line Items]
Net realized gains (losses) on investments sold or redeemed	(106)	(112)	(106)	391
Net unrealized gains (losses) on investments still held	(8,221)	4,601	(21,138)	(3,448)
Equity securities
Gain (Loss) on Securities [Line Items]
Net realized gains (losses) on investments sold or redeemed	0	(227)	1,655	(227)
Net unrealized gains (losses) on investments still held	(20,707)	5,140	(25,014)	9,983
Other investments
Gain (Loss) on Securities [Line Items]
Net realized gains (losses) on investments sold or redeemed	54	2,229	54	2,334
Net unrealized gains (losses) on investments still held	$ (185)	$ 178	$ (421)	$ 1,062