Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Balance	$ 655,167	$ 639,201	$ 618,997	$ 571,921	$ 549,683	$ 579,672	$ 618,997	$ 579,672
Total other comprehensive income (loss), net of tax	(517)	2,286	5,563	5,214	8,918	(22,633)	7,332	(8,501)
Balance	668,096	655,167	639,201	586,406	571,921	549,683	668,096	586,406
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Balance	485		1,290	(2,708)		(3,982)	1,290	(3,982)
Other comprehensive income before reclassifications, net of tax	(2,645)			3,185			(3,365)	4,397
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	7			0			(78)	62
Total other comprehensive income (loss), net of tax	(2,638)			3,185			(3,443)	4,459
Balance	(2,153)	485		477	(2,708)		(2,153)	477
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Balance	(9,202)		(17,521)	(21,473)		(5,863)	(17,521)	(5,863)
Other comprehensive income before reclassifications, net of tax	179			937			4,885	(15,215)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	1,812			929			5,425	1,471
Total other comprehensive income (loss), net of tax	1,991			1,866			10,310	(13,744)
Balance	(7,211)	(9,202)		(19,607)	(21,473)		(7,211)	(19,607)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance	(1,741)		(1,884)	(878)		(983)	(1,884)	(983)
Other comprehensive income before reclassifications, net of tax	0			0
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	72			52			215	157
Total other comprehensive income (loss), net of tax	72			52			215	157
Balance	(1,669)	(1,741)		(826)	(878)		(1,669)	(826)
Accumulated Gain (Loss), Financial Liability, Fair Value Option, Attributable to Parent [Member]
Balance	2,041		1,849	1,537		1,021	1,849	1,021
Other comprehensive income before reclassifications, net of tax	58			111			250	627
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	0			0
Total other comprehensive income (loss), net of tax	58			111			250	627
Balance	2,099	2,041		1,648	1,537		2,099	1,648
AOCI Attributable to Parent [Member]
Balance	(8,417)	(10,703)	(16,266)	(23,522)	(32,440)	(9,807)	(16,266)	(9,807)
Other comprehensive income before reclassifications, net of tax	(2,408)			4,233			1,770	(10,191)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	1,891			981			5,562	1,690
Total other comprehensive income (loss), net of tax	(517)	2,286	5,563	5,214	8,918	(22,633)	7,332	(8,501)
Balance	$ (8,934)	$ (8,417)	$ (10,703)	$ (18,308)	$ (23,522)	$ (32,440)	$ (8,934)	$ (18,308)