Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 146,087	$ 201,193	$ 303,844	$ 382,324
Other comprehensive income (loss), net of tax (Note 15)
Unrealized holding gains (losses) on investments arising during the period for which an allowance for expected losses has not been recognized	(41,125)	(202,665)	24,729	(453,957)
Less: Reclassification adjustment for net gains (losses) on investments included in net income
Net realized gains (losses) on disposals and non-credit related impairment losses	(4,072)	(3,113)	(8,205)	(4,675)
Net unrealized gains (losses) on investments	(37,053)	(199,552)	32,934	(449,282)
Other adjustments to comprehensive income (loss), net	0	0	179	84
Other comprehensive income (loss), net of tax	(37,053)	(199,552)	33,113	(449,198)
Comprehensive income (loss)	$ 109,034	$ 1,641	$ 336,957	$ (66,874)