Shareholders' Equity - Changes in Balances of Component of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ 2,070,789	$ 1,879,141	$ 1,962,327	$ 1,661,847
Other comprehensive income (loss) before reclassification			58,318	42,444
Amounts reclassified from accumulated other comprehensive income (loss)			5,961	148,234
Other comprehensive income (loss), net of tax amount	11,109	62,512	64,279	190,678
Balance	2,114,268	1,980,096	2,114,268	1,980,096
Securities Available for Sale and Transferred Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance			(66,885)	(204,670)
Other comprehensive income (loss) before reclassification			49,952	43,949
Amounts reclassified from accumulated other comprehensive income (loss)			0	137,094
Other comprehensive income (loss), net of tax amount			49,952	181,043
Balance	(16,933)	(23,627)	(16,933)	(23,627)
Defined Benefit Pension Items [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance			(4,721)	(6,075)
Other comprehensive income (loss) before reclassification			0	0
Amounts reclassified from accumulated other comprehensive income (loss)			94	250
Other comprehensive income (loss), net of tax amount			94	250
Balance	(4,627)	(5,825)	(4,627)	(5,825)
Cash Flow Hedge Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance			(12,053)	(8,978)
Other comprehensive income (loss) before reclassification			8,366	(1,505)
Amounts reclassified from accumulated other comprehensive income (loss)			5,867	10,890
Other comprehensive income (loss), net of tax amount			14,233	9,385
Balance	2,180	407	2,180	407
Accumulated Other Comprehensive (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(30,489)	(91,557)	(83,659)	(219,723)
Balance	$ (19,380)	$ (29,045)	$ (19,380)	$ (29,045)