Other Comprehensive Income - Changes in the Components of Other Comprehensive Income (Loss), Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	$ 2,160			$ 1,587			$ 23,052	$ 26,276
Total other comprehensive income (loss), tax expense (benefit)	549			403			5,866	6,686
Other comprehensive income, net of tax	1,611	$ 1,838	$ 13,737	1,184	$ 7,960	$ 10,446	17,186	19,590
Securities available for sale:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, pre-tax	519			(84)			26,404	27,695
Other comprehensive income (loss) before reclassifications, tax expense (benefit)	131			(22)			6,719	7,047
Other comprehensive income (loss), before reclassifications, net of tax	388			(62)			19,685	20,648
Reclassification from AOCI, pre-tax				2,516			(31)	2,511
Reclassification from AOCI, tax expense (benefit)				640			(8)	639
Reclassification from AOCI, net of tax				1,876			(23)	1,872
Total other comprehensive income (loss), pre-tax	519			2,432			26,373	30,206
Total other comprehensive income (loss), tax expense (benefit)	131			618			6,711	7,686
Other comprehensive income, net of tax	388			1,814			19,662	22,520
Derivative instruments:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, pre-tax	1,576						(3,516)	(4,244)
Other comprehensive income (loss) before reclassifications, tax expense (benefit)	401						(895)	(1,080)
Other comprehensive income (loss), before reclassifications, net of tax	1,175						(2,621)	(3,164)
Total other comprehensive income (loss), pre-tax	1,576						(3,516)	(4,244)
Total other comprehensive income (loss), tax expense (benefit)	401						(895)	(1,080)
Other comprehensive income, net of tax	1,175						(2,621)	(3,164)
Amortization of net actuarial loss recognized in net periodic pension cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, pre-tax	65			104			195	314
Reclassification from AOCI, tax expense (benefit)	17			26			50	80
Reclassification from AOCI, net of tax	48			78			145	234
Total defined benefit pension and post-retirement benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	65			104			195	314
Total other comprehensive income (loss), tax expense (benefit)	17			26			50	80
Other comprehensive income, net of tax	$ 48			78			$ 145	$ 234
Derivative instruments:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, pre-tax				(949)
Other comprehensive income (loss) before reclassifications, tax expense (benefit)				(241)
Other comprehensive income (loss), before reclassifications, net of tax				(708)
Total other comprehensive income (loss), pre-tax				(949)
Total other comprehensive income (loss), tax expense (benefit)				(241)
Other comprehensive income, net of tax				$ (708)