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	$ 202,820	$ 154,244	$ 194,451
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	4,800	77,700	3,493
Stock-based compensation expense	14,926	10,737	9,271
Depreciation, amortization and accretion	23,168	14,893	34,213
Investment securities gain, net	(314)	(16,710)	(2,132)
Net realized gain on sale of premises and equipment, loans held for investment and OPPO	(500)	(1,334)	(7,317)
Net realized loss (gain) on sale and valuation adjustments of OREO	(40)	34	602
Gain on bank owned life insurance death benefit	(344)	0	(3,051)
Originations of loans held for sale	(336,455)	(491,385)	(210,484)
Proceeds from sale of loans held-for-sale	352,823	483,130	196,615
Change in Fair Value of Loans Held-for-sale	339	(508)	0
Deferred income tax expense (benefit)	(6,629)	(13,768)	330
Net change in:
Interest receivable	4,049	(7,992)	(1,516)
Interest payable	62	(933)	632
Other assets	6,815	(48,539)	(23,464)
Other liabilities	(30,535)	32,791	14,308
Net cash provided by operating activities	235,065	192,292	204,747
Cash Flows From Investing Activities
Loans originated, net of principal collected	174,463	(619,543)	(291,857)
Investment in low income housing tax credit partnerships	(1,408)	0	0
Purchases of Debt Securities, Available-for-sale	(3,128,233)	(2,118,667)	(1,196,895)
Purchases of Held-to-maturity Securities	(257,503)	0	0
Purchases of loans held for investment	279,734	50,035	57,075
Purchases of premises and equipment	(6,125)	(8,720)	(8,447)
Purchases of Federal Home Loan Bank stock	(1)	(53,240)	(273,800)
Proceeds from Sale of Debt Securities, Available-for-sale	89,219	194,697	259,554
Proceeds from Sale of Equity Securities	0	3,000	0
Proceeds from principal repayments and maturities of securities available for sale	764,253	603,129	428,025
Proceeds from Maturities, Prepayments and Calls of Held-to-maturity Securities	107,578	0	0
Proceeds from sales of premises and equipment and loans held for investment	15,880	2,948	8,634
Proceeds from redemption of Federal Home Loan Bank Stock	7,464	91,080	251,640
Proceeds from sales of other real estate owned and other personal property owned	132	1,074	6,506
Proceeds from bank owned life insurance death benefit	671	1,050	8,265
Proceeds from Termination of Cash Flow Hedging Instrument	0	34,442	0
Net cash received in business combinations	154,984	0	0
Net cash used in investing activities	(2,358,360)	(1,918,785)	(865,450)
Cash Flows From Financing Activities
Net increase in deposits	2,402,669	3,185,167	226,958
Net increase in sweep repurchase agreements	12,154	9,422	3,343
Proceeds from employee stock purchase plan	2,350	2,028	2,025
Proceeds from Federal Home Loan Bank advances	30	1,331,000	6,845,000
Proceeds from Federal Reserve Bank borrowings	40	222,010	36,000
Proceeds from other borrowings	0	9,222	100
Payments for Federal Home Loan Bank advances	(30)	(2,277,000)	(6,291,000)
Payments for Federal Reserve Bank borrowings	(40)	(222,010)	(36,000)
Payments for other borrowings	0	(9,222)	(100)
Payments for common stock dividends	(83,790)	(95,509)	(101,911)
Repayments of Subordinated Debt	(35,000)	0	0
Payments for purchase of treasury stock	0	(20,000)	(50,834)
Payments for purchase and retirement of common stock	4,140	2,522	2,792
Net cash provided by financing activities	2,294,243	2,132,586	630,789
Increase (decrease) in cash and cash equivalents	170,948	406,093	(29,914)
Cash and cash equivalents at beginning of period	653,766	247,673	277,587
Supplemental Information:
Interest paid	8,484	18,631	35,916
Income taxes paid, net of refunds	60,562	43,287	47,375
Non-cash investing and financing activities:
Transfer of debt securities AFS to HTM	2,012,123	0	0
Loans transferred to OREO	0	1,033	386
Common stock issued in connection with acquistion	256,061	0	0
Premises and equipment expenditures incurred but not yet paid	63	302	451
Change in dividends payable on unvested shares included in other liabilities	$ 51	$ 706	$ 354