Other Comprehensive Income (Loss) - Schedule of Activity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances	$ 728,253	$ 698,029	$ 717,689	$ 663,054
Other comprehensive (loss) income before reclassifications	(7,852)	(3,303)	(24,609)	18,563
Amounts reclassified from accumulated other comprehensive (loss) income	640	487	1,589	1,137
Other comprehensive (loss) income	(7,212)	(2,816)	(23,020)	19,700
Ending balances	722,357	713,611	722,357	713,611
Available-for- Sale Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances	3,603	25,581	20,609	4,039
Other comprehensive (loss) income before reclassifications	(7,852)	(3,303)	(24,609)	18,563
Amounts reclassified from accumulated other comprehensive (loss) income	41	0	(208)	(324)
Other comprehensive (loss) income	(7,811)	(3,303)	(24,817)	18,239
Ending balances	(4,208)	22,278	(4,208)	22,278
Employee Benefit Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances	(51,485)	(46,629)	(52,683)	(47,603)
Other comprehensive (loss) income before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive (loss) income	599	487	1,797	1,461
Other comprehensive (loss) income	599	487	1,797	1,461
Ending balances	(50,886)	(46,142)	(50,886)	(46,142)
Accumulated Other Comprehensive (Loss) Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances	(47,882)	(21,048)	(32,074)	(43,564)
Other comprehensive (loss) income	(7,212)	(2,816)	(23,020)	19,700
Ending balances	$ (55,094)	$ (23,864)	$ (55,094)	$ (23,864)