Business Segments - Selected Business Segment Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Business segment financial information
Net Interest Income	$ 135,955	$ 125,263
Provision for Credit Losses	2,000	(5,500)
Net Interest Income (Loss) After Provision for Credit Losses	133,955	130,763
Noninterest Income	40,737	43,551
Noninterest Expense	(111,919)	(103,874)
Income (Loss) Before Provision for Income Taxes	62,773	70,440
Provision for Income Taxes	(15,931)	(15,606)
Net Income (Loss)	46,842	54,834
Total Assets	23,931,977	23,000,317	$ 23,606,877
Consumer Banking
Business segment financial information
Net Interest Income	98,008	70,361
Provision for Credit Losses	2,669	1,683
Net Interest Income (Loss) After Provision for Credit Losses	95,339	68,678
Noninterest Income	31,154	31,969
Noninterest Expense	(85,073)	(81,810)
Income (Loss) Before Provision for Income Taxes	41,420	18,837
Provision for Income Taxes	(10,623)	(4,714)
Net Income (Loss)	30,797	14,123
Total Assets	8,654,243	7,927,186
Commercial Banking
Business segment financial information
Net Interest Income	56,705	46,349
Provision for Credit Losses	(1)	(197)
Net Interest Income (Loss) After Provision for Credit Losses	56,706	46,546
Noninterest Income	8,649	10,198
Noninterest Expense	(20,289)	(18,669)
Income (Loss) Before Provision for Income Taxes	45,066	38,075
Provision for Income Taxes	(10,793)	(9,197)
Net Income (Loss)	34,273	28,878
Total Assets	5,625,254	5,174,115
Treasury and Other
Business segment financial information
Net Interest Income	(18,758)	8,553
Provision for Credit Losses	(668)	(6,986)
Net Interest Income (Loss) After Provision for Credit Losses	(18,090)	15,539
Noninterest Income	934	1,384
Noninterest Expense	(6,557)	(3,395)
Income (Loss) Before Provision for Income Taxes	(23,713)	13,528
Provision for Income Taxes	5,485	(1,695)
Net Income (Loss)	(18,228)	11,833
Total Assets	$ 9,652,480	$ 9,899,016