Reclassification Adjustments Out of Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reclassification Adjustments out of AOCI [Abstract]
Net securities (gains) losses	$ (566)	$ 388	$ (4,213)
Interest income (expense)	321,088	315,678	311,555
Other noninterest expense	20,339	24,863	24,440
Income tax (benefit) expense	44,973	28,699	34,411
Net Income	154,885	104,388	121,021
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustments out of AOCI [Abstract]
Total reclassifications, net of tax	1,478	1,923	1,117
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustments out of AOCI [Abstract]
Income tax (benefit) expense	(145)	(160)	(204)
Net Income	432	481	612
Gains (losses) on AFS Securities [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustments out of AOCI [Abstract]
Net securities (gains) losses	0	(3)	79
Amortization of Unrealized Gains Related to Securities Transfer [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustments out of AOCI [Abstract]
Interest income (expense)	577	644	737
Net Unrealized Losses (Gains) on Cash Flow Hedges Reclassified to Interest Expense [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustments out of AOCI [Abstract]
Interest income (expense)	21	296	(2,012)
Income tax (benefit) expense	(5)	(74)	503
Net Income	16	222	(1,509)
Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustments out of AOCI [Abstract]
Income tax (benefit) expense	(343)	(407)	(672)
Net Income	1,030	1,220	2,014
Amortization of Net Losses [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustments out of AOCI [Abstract]
Other noninterest expense	1,263	1,535	2,593
Amortization of Prior Service Costs [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustments out of AOCI [Abstract]
Other noninterest expense	$ 110	$ 92	$ 93