Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 603,119	$ 742,934	$ 600,671
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	114,917	(584,856)	(138,435)
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	(10,852)	(7,880)	4,472
Net decrease (increase) in expected credit losses	0	0	725
Net unrealized gains (losses) on investments	125,769	(576,976)	(143,632)
Other adjustments to comprehensive income (loss), net	179	84	0
Other comprehensive income (loss), net of tax	125,948	(576,892)	(143,632)
Comprehensive income	$ 729,067	$ 166,042	$ 457,039