Shareholders' Equity - Changes in Balances of Component of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ 1,492,268	$ 1,741,311
Other comprehensive income (loss) before reclassification	30,726	(116,353)
Amounts reclassified from accumulated other comprehensive income (loss)	2,296	257
Other comprehensive income (loss), net of tax amount	33,022	(116,096)
Balance	1,562,099	1,631,382
Securities Available for Sale and Transferred Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(254,442)	(17,774)
Other comprehensive income (loss) before reclassification	26,024	(116,353)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Other comprehensive income (loss), net of tax amount	26,024	(116,353)
Balance	(228,418)	(134,127)
Defined Benefit Pension Items [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(5,792)	(14,786)
Other comprehensive income (loss) before reclassification	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	98	257
Other comprehensive income (loss), net of tax amount	98	257
Balance	(5,694)	(14,529)
Cash Flow Hedge Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(15,169)	0
Other comprehensive income (loss) before reclassification	4,702	0
Amounts reclassified from accumulated other comprehensive income (loss)	2,198	0
Other comprehensive income (loss), net of tax amount	6,900	0
Balance	(8,269)	0
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(275,403)	(32,560)
Balance	$ (242,381)	$ (148,656)