Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	$ 275,497	$ 178,040	$ 226,339
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	(14,600)	76,920	32,825
Depreciation and amortization of premises and equipment	28,802	28,803	28,200
Amortization of TCI	28,003	30,800	32,810
Net amortization of investment securities premiums	16,031	12,222	9,387
Deferred income tax benefit	12,410	(21,591)	(165)
Investment securities gains, net	(33,516)	(3,053)	(4,733)
Gain on sales of mortgage loans held for sale	(24,379)	(53,599)	(17,882)
Proceeds from sales of mortgage loans held for sale	1,050,943	1,536,174	916,725
Originations of mortgage loans held for sale	(978,446)	(1,528,633)	(909,572)
Intangible amortization	589	529	1,427
Amortization of issuance costs and discounts on long-term borrowings	1,846	1,128	842
Debt extinguishment costs	33,249	2,877	0
Stock-based compensation	8,402	7,529	7,413
Other changes, net	(62,559)	(110,781)	(195,903)
Total adjustments	66,775	(20,675)	(98,626)
Net cash provided by operating activities	342,272	157,365	127,713
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sales of AFS securities	359,137	215,150	710,739
Proceeds from principal repayments and maturities of AFS securities	469,393	430,845	234,702
Proceeds from principal repayments and maturities of HTM securities	117,958	93,823	83,121
Purchase of AFS securities	(1,309,470)	(1,134,380)	(1,138,070)
Purchase of HTM securities	(443,081)	0	0
Sale of Visa Shares	33,962	0	0
Sale (purchase) of FRB and FHLB stock	34,494	5,293	(18,139)
Net decrease (increase) in loans	561,664	(2,072,831)	(708,048)
Net purchases of premises and equipment	(17,679)	(20,237)	(33,717)
Net cash paid for acquisition	(1,982)	(1,884)	(5,174)
Net change in tax credit investments	(18,363)	(15,259)	(18,760)
Net cash used in investing activities	(213,967)	(2,499,480)	(893,346)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in demand and savings deposits	1,315,139	3,951,905	849,437
Net (decrease) increase in time deposits	(580,847)	(506,611)	168,317
Net (decrease) increase in short-term borrowings	(213,302)	(253,175)	128,464
Proceeds from long-term borrowings	620	495,898	485,000
Repayments of long-term borrowings	(710,633)	(85,410)	(596,056)
Net proceeds from issuance of preferred stock	0	192,878	0
Net proceeds from issuance of common stock	7,437	7,375	6,362
Dividends paid	(112,028)	(90,956)	(92,330)
Acquisition of treasury stock	(43,909)	(39,748)	(111,457)
Net cash (used in) provided by financing activities	(337,523)	3,672,156	837,737
Net Increase in Cash and Cash Equivalents	(209,218)	1,330,041	72,104
Cash and Cash Equivalents at Beginning of Year	1,847,832	517,791	445,687
Cash and Cash Equivalents at End of Year	1,638,614	1,847,832	517,791
Cash paid during period for:
Interest	63,047	112,140	178,612
Income taxes	27,870	16,190	9,193
Supplemental schedule of certain noncash activities
Transfer of AFS securities to HTM securities	376,165	0	0
Transfer of HTM securities to AFS securities	$ 0	$ 0	$ 158,898