Business Segments - Selected Business Segment Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Business segment financial information
Net Interest Income (Expense)	$ 125,807	$ 113,938
Provision for (Recapture of) Credit Losses	3,250	2,000
Net Interest Income (Expense) After Provision for Credit Losses	122,557	111,938
Noninterest Income	44,058	42,285
Salaries and Benefits	62,884	58,215
Net Occupancy	10,559	10,456
Other Noninterest Expense	37,016	37,188
Noninterest Expense	110,459	105,859
Income (Loss) Before Income Taxes	56,156	48,364
Provision (Benefit) for Income Taxes	12,171	11,973
Net Income (Loss)	43,985	36,391
Total Assets	23,885,056	23,420,860	$ 23,601,114
Consumer Banking
Business segment financial information
Net Interest Income (Expense)	95,624	96,994
Provision for (Recapture of) Credit Losses	3,295	2,287
Net Interest Income (Expense) After Provision for Credit Losses	92,329	94,707
Noninterest Income	33,498	31,982
Salaries and Benefits	21,105	20,917
Net Occupancy	7,067	6,864
Other Noninterest Expense	58,202	54,924
Noninterest Expense	86,374	82,705
Income (Loss) Before Income Taxes	39,453	43,984
Provision (Benefit) for Income Taxes	10,001	11,181
Net Income (Loss)	29,452	32,803
Total Assets	8,246,158	8,396,623
Commercial Banking
Business segment financial information
Net Interest Income (Expense)	55,574	51,493
Provision for (Recapture of) Credit Losses	1,108	(6)
Net Interest Income (Expense) After Provision for Credit Losses	54,466	51,499
Noninterest Income	7,734	6,794
Salaries and Benefits	5,360	5,516
Net Occupancy	400	447
Other Noninterest Expense	13,882	12,680
Noninterest Expense	19,642	18,643
Income (Loss) Before Income Taxes	42,558	39,650
Provision (Benefit) for Income Taxes	10,869	10,008
Net Income (Loss)	31,689	29,642
Total Assets	6,219,971	5,830,056
Treasury and Other
Business segment financial information
Net Interest Income (Expense)	(25,391)	(34,549)
Provision for (Recapture of) Credit Losses	(1,153)	(281)
Net Interest Income (Expense) After Provision for Credit Losses	(24,238)	(34,268)
Noninterest Income	2,826	3,509
Salaries and Benefits	36,419	31,782
Net Occupancy	3,092	3,145
Other Noninterest Expense	(35,068)	(30,416)
Noninterest Expense	4,443	4,511
Income (Loss) Before Income Taxes	(25,855)	(35,270)
Provision (Benefit) for Income Taxes	(8,699)	(9,216)
Net Income (Loss)	(17,156)	(26,054)
Total Assets	$ 9,418,927	$ 9,194,181