Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Cash flows from operating activities
Net income	$ 81,169	$ 103,360
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	24,001	17,971
Depreciation and amortization	12,352	11,425
Change in MSRs valuation	(1,646)	1,857
Amortization of other intangible assets	2,203	2,203
Amortization and accretion on earning assets, funding, and other, net	10,673	338
Net amortization of tax credit investments	8,990	8,574
(Gains) on sales of investment securities, net	(3,857)	0
Asset losses (gains), net	306	(263)
(Gains) loss on mortgage banking activities, net	(22)	251
Mortgage loans originated and acquired for sale	(105,394)	(69,254)
Proceeds from sales of mortgage loans held for sale	91,026	54,652
Changes in certain assets and liabilities:
Decrease (increase) in interest receivable	2,477	(7,955)
Increase in interest payable	15,590	14,775
(Decrease) in expense payable	(30,827)	(52,396)
Increase (decrease) in net derivative position	35,008	(42,403)
Net change in other assets and other liabilities	12,453	4,336
Net cash provided by operating activities	154,500	47,470
Cash flows from investing activities
Net (increase) in loans	(222,656)	(414,268)
Purchases of:
AFS securities	(341,275)	(681,386)
HTM securities	0	(41,524)
FHLB and Federal Reserve Bank stocks and equity securities	(16,585)	(56,892)
Proceeds from:
Sales of AFS securities	9,472	0
Sale of FHLB and Federal Reserve Bank stocks and equity securities	98,005	15,765
Prepayments, calls, and maturities of AFS securities	176,266	79,746
Prepayments, calls, and maturities of HTM securities	28,026	33,053
Sales, prepayments, calls, and maturities of other assets	4,337	10,115
Premises, equipment, and software	(8,500)	(13,898)
Net change in tax credit and alternative investments	(2,409)	(7,033)
Net cash (used in) investing activities	(275,320)	(1,076,322)
Cash flows from financing activities
Net increase in deposits	267,109	695,723
Net increase (decrease) in short-term funding	438,891	(379,329)
Net (decrease) increase in short-term FHLB advances	(602,000)	660,000
Repayment of long-term FHLB advances	(664)	(507)
Proceeds from long-term FHLB advances	619	115
Proceeds from issuance of long-term funding	0	292,740
(Repayment) of finance lease principal	(22)	(21)
Proceeds from issuance of common stock for stock-based compensation plans	3,910	1,766
Cash dividends on common stock	(33,527)	(32,013)
Cash dividends on preferred stock	(2,875)	(2,875)
Net cash provided by financing activities	48,580	1,230,238
Net (decrease) increase in cash and cash equivalents	(72,239)	201,385
Cash and cash equivalents at beginning of period	923,823	621,455	$ 621,455
Cash and cash equivalents at end of period(a)	851,583	822,840	923,823
Supplemental disclosures of cash flow information
Cash paid for interest	249,660	153,760
Cash paid for income and franchise taxes	1,995	1,086
Loans and bank premises transferred to OREO	577	3,599
Capitalized mortgage servicing rights	877	474	$ 3,564
Loans transferred (from) into held for sale from (into) portfolio, net	(86,096)	94
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	(16,326)	10,331
Board Authorized Purchase Program [Member]
Cash flows from financing activities
Purchase of treasury stock, open market purchases	(18,289)	0
Other Assets [Member]
Supplemental disclosures of cash flow information
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	2,708	(341)
Other Liabilities [Member]
Supplemental disclosures of cash flow information
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	10,210	(10,724)
Performance/Service Based RSAs, RSA,
Cash flows from financing activities
Purchase of treasury stock, open market purchases	(4,572)	(5,362)
Retained Earnings [Member]
Cash flows from operating activities
Net income	$ 81,169	$ 103,360