Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Cash flows from operating activities
Net income	$ 83,248	$ 103,360	$ 96,275	$ 74,262	$ 273,762	$ 257,360
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	21,943		16,998		62,014	13,006
Depreciation and amortization					34,703	33,743
Change in MSRs valuation					(14,658)	(22,348)
Amortization of other intangible assets	2,203		2,203		6,608	6,608
Amortization and accretion on earning assets, funding, and other, net					27,394	13,280
Net amortization of tax credit investments					25,830	25,916
(Gains) on sales of investment securities, net					0	(260)
Asset (gains), net	(625)		(18)		(590)	(1,883)
Loss on mortgage banking activities, net					2,154	5,712
Mortgage loans originated and acquired for sale					(283,469)	(535,694)
Proceeds from sales of mortgage loans held for sale					254,619	620,352
Changes in certain assets and liabilities:
(Increase) in interest receivable					(26,670)	(35,254)
Increase in interest payable					69,461	1,795
(Decrease) in expense payable					(22,632)	(17,994)
Increase in net derivative position					3,721	320,972
Net change in other assets and other liabilities					(34,137)	37,018
Net cash provided by operating activities					378,110	722,330
Cash flows from investing activities
Net (increase) in loans					(1,436,901)	(3,595,331)
Purchases of:
AFS securities					(1,109,501)	(510,301)
HTM securities					(41,524)	(245,826)
FHLB and Federal Reserve Bank stocks and equity securities					(114,985)	(112,157)
Proceeds from:
Sales of AFS securities					0	1,061
Sale of FHLB and Federal Reserve Bank stocks and equity securities					131,272	259
Prepayments, calls, and maturities of AFS securities					288,313	392,275
Prepayments, calls, and maturities of HTM securities					101,847	153,163
Sales, prepayments, calls, and maturities of other assets					20,224	31,732
Premises, equipment, and software, net of disposals					(43,541)	(45,441)
Net change in tax credit and alternative investments					(19,615)	(50,386)
Net cash (used in) investing activities					(2,224,411)	(3,980,951)
Cash flows from financing activities
Net increase in deposits					2,487,225	732,347
Net (decrease) in short-term funding					(154,292)	(69,902)
Net increase (decrease) in short-term FHLB advances					(580,000)	2,583,000
Repayment of long-term FHLB advances					(568)	(413,523)
Proceeds from long-term FHLB advances					1,369	1,356
Proceeds from issuance of long-term funding					292,740	0
(Repayment) proceeds of finance lease principal					(64)	327
Proceeds from issuance of common stock for stock-based compensation plans					2,362	8,059
Cash dividends on common stock					(96,005)	(91,256)
Cash dividends on preferred stock					(8,625)	(8,625)
Net cash provided by financing activities					1,937,635	2,735,525
Net increase (decrease) in cash and cash equivalents					91,334	(523,096)
Cash and cash equivalents at beginning of period		621,455		1,025,515	621,455	1,025,515	$ 1,025,515
Cash and cash equivalents at end of period(a)	712,789		502,419		712,789	502,419	621,455
Supplemental disclosures of cash flow information
Cash paid for interest					576,221	83,337
Cash paid for income and franchise taxes					68,382	6,087
Loans and bank premises transferred to OREO					5,917	5,052
Capitalized mortgage servicing rights					2,477	6,316	$ 7,279
Loans transferred into held for sale from portfolio, net					6,833	1,789
Transfer of AFS securities to HTM securities					0	1,621,990
Unsettled trades to purchase securities					0	4,130
Gain on sale and net write-up (down) of equity securities					0	5,690
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	(6,762)		0		(19,391)	0
Other Assets [Member]
Supplemental disclosures of cash flow information
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge					3,308	10,610
Other Liabilities [Member]
Supplemental disclosures of cash flow information
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge					18,652	14,703
Performance/Service Based RSAs, RSA,
Cash flows from financing activities
Purchase of treasury stock, open market purchases					(6,507)	(6,259)
Retained Earnings [Member]
Cash flows from operating activities
Net income	$ 83,248	$ 103,360	$ 96,275	$ 74,262	$ 273,762	$ 257,360