Investments - Net Realized and Unrealized Gains (Losses) on Investment (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Gain (Loss) on Securities [Line Items]
Equity securities, gross gains	$ 217		$ 106	$ 3,876	$ 5,168
Equity securities, gross losses	(63)		(3,001)	(875)	(3,638)
Equity securities, net	154		(2,895)	3,001	1,530
Net realized and unrealized gains (losses) on investment, gross gains	1,201		2,293	8,530	12,143
Net realized and unrealized gains (losses) on investment, gross losses	(2,773)		(3,230)	(5,682)	(4,130)
Net realized and unrealized investment (losses) gains	(1,572)		(937)	2,848	8,013
Net gains recognized for equity securities divested	0		0	0	(441)
Unrealized gains (losses) recognized for equity securities still held at reporting date	154		(2,895)	3,001	1,089
Proceeds from sales of fixed maturities classified as available-for-sale	35,107		126,282	139,645	332,636
Equity method investments	0			0		$ (4,414)
Total net unrealized losses	(60,341)			(60,341)		(2,613)
Deferred income tax	216			216
Deferred income tax						(80)
Net unrealized losses, net of deferred income tax	(60,125)			(60,125)		(2,693)
Change, net of deferred income tax		$ (52,050)		(57,432)
Fixed maturity investments
Gain (Loss) on Securities [Line Items]
Fixed maturities, gross gains	591		1,890	1,829	6,137
Fixed maturities, gross losses	(495)		(99)	(637)	(343)
Fixed maturities, net	96		1,791	1,192	5,794
Other investments
Gain (Loss) on Securities [Line Items]
Other investments, gross gains	393		297	2,825	838
Other investments, gross losses	(2,215)		(130)	(4,170)	(149)
Other investments, net	(1,822)		$ 167	(1,345)	$ 689
Available-for-sale securities | Fixed maturity investments
Gain (Loss) on Securities [Line Items]
Fixed maturity investments	$ (60,341)			$ (60,341)		$ 1,801