Other Comprehensive Income (Loss) - Changes in the Components of Other Comprehensive Income (Loss), Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	$ 18,423	$ 14,010
Total other comprehensive income (loss), tax expense (benefit)	4,686	3,564
Other comprehensive income, net of tax	13,737	10,446
Securities available for sale:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, pre-tax	22,389	15,179
Other comprehensive income (loss) before reclassifications, tax expense (benefit)	5,695	3,862
Other comprehensive income (loss), before reclassifications, net of tax	16,694	11,317
Reclassification from AOCI, pre-tax	0	(13)
Reclassification from AOCI, tax expense (benefit)	0	(3)
Reclassification from AOCI, net of tax	0	(10)
Total other comprehensive income (loss), pre-tax	22,389	15,166
Total other comprehensive income (loss), tax expense (benefit)	5,695	3,859
Other comprehensive income, net of tax	16,694	11,307
Derivative instruments:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, pre-tax	(4,028)
Other comprehensive income (loss) before reclassifications, tax expense (benefit)	(1,025)
Other comprehensive income (loss), before reclassifications, net of tax	(3,003)
Total other comprehensive income (loss), pre-tax	(4,028)
Total other comprehensive income (loss), tax expense (benefit)	(1,025)
Other comprehensive income, net of tax	(3,003)
Amortization of net actuarial loss recognized in net periodic pension cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, pre-tax	62	72
Reclassification from AOCI, tax expense (benefit)	16	18
Reclassification from AOCI, net of tax	46	54
Total defined benefit pension and post-retirement benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	62	72
Total other comprehensive income (loss), tax expense (benefit)	16	18
Other comprehensive income, net of tax	$ 46	54
Derivative instruments:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, pre-tax		(1,228)
Other comprehensive income (loss) before reclassifications, tax expense (benefit)		(313)
Other comprehensive income (loss), before reclassifications, net of tax		(915)
Total other comprehensive income (loss), pre-tax		(1,228)
Total other comprehensive income (loss), tax expense (benefit)		(313)
Other comprehensive income, net of tax		$ (915)