Shareholders' Equity - Changes in Balances of Component of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ 1,741,311	$ 1,741,117	$ 1,660,702
Other comprehensive income (loss) before reclassification	244,088	(32,971)	21,502
Amounts reclassified from accumulated other comprehensive income (loss)	1,245	1,462	1,047
Other comprehensive income (loss), net of tax amount	242,843	(31,509)	22,549
Balance	1,492,268	1,741,311	1,741,117
Securities Available for Sale and Transferred Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(17,774)	17,331	(8,017)
Other comprehensive income (loss) before reclassification	(236,668)	(35,105)	25,348
Other comprehensive income (loss), net of tax amount	(236,668)	(35,105)	25,348
Balance	(254,442)	(17,774)	17,331
Defined Benefit Pension Items [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(14,786)	(18,382)	(15,583)
Other comprehensive income (loss) before reclassification	8,094	2,134	(3,846)
Amounts reclassified from accumulated other comprehensive income (loss)	900	1,462	1,047
Other comprehensive income (loss), net of tax amount	8,994	3,596	(2,799)
Balance	(5,792)	(14,786)	(18,382)
Cash Flow Hedge Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance			0
Other comprehensive income (loss) before reclassification	(15,514)
Amounts reclassified from accumulated other comprehensive income (loss)	(345)
Other comprehensive income (loss), net of tax amount	(15,169)
Balance	(15,169)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(32,560)	(1,051)	(23,600)
Balance	$ (275,403)	$ (32,560)	$ (1,051)