Business Segments - Selected Business Segment Financial Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Business segment financial information
Net Interest Income	$ 540,558	$ 497,290	$ 496,322
Provision for Credit Losses	(7,800)	(50,500)	117,800
Net Interest Income (Loss) After Provision for Credit Losses	548,358	547,790	378,522
Noninterest Income	157,541	171,353	184,409
Noninterest Expense	(415,265)	(393,589)	(373,807)
Income (Loss) Before Provision for Income Taxes	290,634	325,554	189,124
Provision for Income Taxes	(64,830)	(72,182)	(35,320)
Net Income	225,804	253,372	153,804
Total Assets	23,606,877	22,784,941	20,603,651
Consumer Banking
Business segment financial information
Net Interest Income	327,940	284,597	293,451
Provision for Credit Losses	5,324	5,764	8,087
Net Interest Income (Loss) After Provision for Credit Losses	322,616	278,833	285,364
Noninterest Income	126,336	131,292	128,399
Noninterest Expense	(330,561)	(304,177)	(289,590)
Income (Loss) Before Provision for Income Taxes	118,391	105,948	124,173
Provision for Income Taxes	(29,974)	(26,474)	(31,563)
Net Income	88,417	79,474	92,610
Total Assets	8,545,896	7,701,447	7,507,825
Commercial Banking
Business segment financial information
Net Interest Income	209,272	194,409	188,626
Provision for Credit Losses	(205)	201	(948)
Net Interest Income (Loss) After Provision for Credit Losses	209,477	194,208	189,574
Noninterest Income	25,937	30,637	34,523
Noninterest Expense	(70,601)	(64,470)	(63,294)
Income (Loss) Before Provision for Income Taxes	164,813	160,375	160,803
Provision for Income Taxes	(40,659)	(39,070)	(40,081)
Net Income	124,154	121,305	120,722
Total Assets	5,522,916	5,107,001	5,116,807
Treasury and Other
Business segment financial information
Net Interest Income	3,346	18,284	14,245
Provision for Credit Losses	(12,919)	(56,465)	110,661
Net Interest Income (Loss) After Provision for Credit Losses	16,265	74,749	(96,416)
Noninterest Income	5,268	9,424	21,487
Noninterest Expense	(14,103)	(24,942)	(20,923)
Income (Loss) Before Provision for Income Taxes	7,430	59,231	(95,852)
Provision for Income Taxes	5,803	(6,638)	36,324
Net Income	13,233	52,593	(59,528)
Total Assets	$ 9,538,065	$ 9,976,493	$ 7,979,019