Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Balance	$ 670,247	$ 672,345	$ 677,157	$ 670,812	$ 675,813	$ 679,628	$ 677,157	$ 679,628
Other comprehensive loss, net of tax:	(4,912)	1,765	(1,296)	(15,030)	(15,760)	(8,820)	(4,443)	(39,610)
Balance	666,521	670,247	672,345	670,719	670,812	675,813	666,521	670,719
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Balance	(63,523)		(63,106)	(50,133)		(6,272)	(63,106)	(6,272)
Other comprehensive income before reclassifications, net of tax	(6,928)			(22,797)			(11,144)	(66,658)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	1,530			0			5,329
Other comprehensive loss, net of tax:	(5,398)			(22,797)			(5,815)	(66,658)
Balance	(68,921)	(63,523)		(72,930)	(50,133)		(68,921)	(72,930)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Balance	26,559		25,380	18,260		(1,406)	25,380	(1,406)
Other comprehensive income before reclassifications, net of tax	5,162			7,480			14,050	23,657
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(4,868)			710			(12,577)	4,199
Other comprehensive loss, net of tax:	294			8,190			1,473	27,856
Balance	26,853	26,559		26,450	18,260		26,853	26,450
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance	(413)		(275)	(1,313)		(1,282)	(275)	(1,282)
Other comprehensive income before reclassifications, net of tax				0
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(69)			(9)			(207)	(40)
Other comprehensive loss, net of tax:	(69)			(9)			(207)	(40)
Balance	(482)	(413)		(1,322)	(1,313)		(482)	(1,322)
Accumulated Gain (Loss), Financial Liability, Fair Value Option, Attributable to Parent [Member]
Balance	1,358		1,513	1,922		2,276	1,513	2,276
Other comprehensive income before reclassifications, net of tax	261			(414)			106	(768)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax				0
Other comprehensive loss, net of tax:	261			(414)			106	(768)
Balance	1,619	1,358		1,508	1,922		1,619	1,508
AOCI Attributable to Parent [Member]
Balance	(36,019)	(37,784)	(36,488)	(31,264)	(15,504)	(6,684)	(36,488)	(6,684)
Other comprehensive income before reclassifications, net of tax	(1,505)			(15,731)			3,012	(43,769)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(3,407)			701			(7,455)	4,159
Other comprehensive loss, net of tax:	(4,912)	1,765	(1,296)	(15,030)	(15,760)	(8,820)	(4,443)	(39,610)
Balance	$ (40,931)	$ (36,019)	$ (37,784)	$ (46,294)	$ (31,264)	$ (15,504)	$ (40,931)	$ (46,294)