Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Before Tax
Unrealized holding gains (losses) on investments arising during the period for which an allowance for expected credit losses has not been recognized	$ (21,825)	$ (52,056)	$ (65,480)	$ 31,303
Net realized gains (losses) on disposals and non-credit related impairment losses	(3,071)	(5,154)	(6,755)	(10,386)
Net unrealized gains (losses) on investments	(18,754)	(46,902)	(58,725)	41,689
Other adjustments to comprehensive income (loss), net	0	0	(86)	227
Other comprehensive income (loss)	(18,754)	(46,902)	(58,811)	41,916
Tax Effect
Unrealized holding gains (losses) on investments arising during the period for which an allowance for expected credit losses has not been recognized	(4,583)	(10,931)	(13,751)	6,574
Net realized gains (losses) on disposals and non-credit related impairment losses	(644)	(1,082)	(1,418)	(2,181)
Net unrealized gains (losses) on investments	(3,939)	(9,849)	(12,333)	8,755
Other adjustments to comprehensive income (loss), net	0	0	(18)	48
Other comprehensive income (loss)	(3,939)	(9,849)	(12,351)	8,803
Net of Tax
Balance at beginning and end of the period	(377,311)		(377,311)			$ (330,851)
Unrealized holding gains (losses) on investments arising during the period for which an allowance for expected credit losses has not been recognized	(17,242)	(41,125)	(51,729)	24,729
Net realized gains (losses) on disposals and non-credit related impairment losses	(2,427)	(4,072)	(5,337)	(8,205)
Net unrealized gains (losses) on investments	(14,815)	(37,053)	(46,392)	32,934
Other adjustments to other comprehensive income (loss)	0	0	(68)	179
Other comprehensive income (loss), net of tax	(14,815)	(37,053)	(46,460)	33,113
AOCI Attributable to Parent
Before Tax
Balance at beginning of period	(458,856)	(489,410)	(418,799)	(578,228)
Balance at end of period	(477,610)	(536,312)	(477,610)	(536,312)
Tax Effect
Balance at beginning of period	(96,360)	(102,777)	(87,948)	(121,429)
Balance at end of period	(100,299)	(112,626)	(100,299)	(112,626)
Net of Tax
Balance at beginning and end of the period	(377,311)	(423,686)	(377,311)	(423,686)	$ (362,496)	$ (330,851)	$ (386,633)	$ (456,799)
Net unrealized gains (losses) on investments	$ (14,815)	$ (37,053)	$ (46,392)	$ 32,934