Other Comprehensive Income (Loss) - Changes in AOCI (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 1,046,042	$ 715,067	$ 655,254	$ 663,558	$ 715,067	$ 663,558
Other Comprehensive Income (Loss) Before Reclassification	2,121		(8,103)		12,904	(27,970)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	0		27,189		0	27,161
Total Other Comprehensive Income (Loss)	2,121	10,783	19,086	(19,895)	12,904	(809)
Ending balance	1,069,504	1,046,042	687,821	655,254	1,069,504	687,821
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(209,681)	(220,464)	(236,955)	(217,060)	(220,464)	(217,060)
Total Other Comprehensive Income (Loss)	2,121	10,783	19,086	(19,895)
Ending balance	(207,560)	(209,681)	(217,869)	(236,955)	(207,560)	(217,869)
Unrealized Gains and Losses on Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(209,167)	(219,950)	(236,441)	(216,546)	(219,950)	(216,546)
Other Comprehensive Income (Loss) Before Reclassification	2,121		(8,103)		12,904	(27,970)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	0		27,189		0	27,161
Total Other Comprehensive Income (Loss)	2,121		19,086		12,904	(809)
Ending balance	(207,046)	(209,167)	(217,355)	(236,441)	(207,046)	(217,355)
Postretirement Benefit Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(514)	(514)	(514)	(514)	(514)	(514)
Other Comprehensive Income (Loss) Before Reclassification	0		0		0	0
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	0		0		0	0
Total Other Comprehensive Income (Loss)	0		0		0	0
Ending balance	$ (514)	$ (514)	$ (514)	$ (514)	$ (514)	$ (514)

Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 7: http://www.xbrl.org/2003/role/exampleRef
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+ Details