Accumulated Other Comprehensive (Loss) Income - Reclassifications out of AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reclassifications out of accumulated other comprehensive income, net of tax
Salaries and employee benefits	$ (583,398)	$ (554,704)	$ (552,030)
Provision for income taxes	136,544	137,313	128,736
Net income	494,308	496,049	475,543
Amount Reclassified from Accumulated Other Comprehensive Income (Loss)
Reclassifications out of accumulated other comprehensive income, net of tax
Net income	181	85	55
Gains on sales of available for sale securities | Amount Reclassified from Accumulated Other Comprehensive Income (Loss)
Reclassifications out of accumulated other comprehensive income, net of tax
Securities gains, net	(43)	(30)	(102)
Provision for income taxes	(10)	(7)	(24)
Net income	(33)	(23)	(78)
Losses and amortization of defined benefit pension | Amount Reclassified from Accumulated Other Comprehensive Income (Loss)
Reclassifications out of accumulated other comprehensive income, net of tax
Salaries and employee benefits	285	143	174
Provision for income taxes	71	35	41
Net income	$ 214	$ 108	$ 133