CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net income (loss)	$ 164,970	$ (73,351)
Adjustments to net income:
Depreciation and amortization expense	8,081	5,525
Provision for credit losses	(36,502)	186,089
Share-based compensation expense	6,562	4,848
Loss on sales and disposals of premises and equipment	71	211
Loss on sale of or write down of other real estate owned	0	55
Net amortization on securities	11,219	3,739
Net (accretion) of discounts/premiums for acquired loans and deferred loan fees/costs	(21,409)	(9,652)
Gain on sales of investment securities available-for-sale	(9,131)	(7,739)
Loss on debt extinguishment	1,150	0
Originations of loans held for sale	(20,264)	(10,163)
Proceeds from the sales of and principal payments from loans held for sale	17,609	13,490
(Gain) loss on sales of loans	(1,907)	1,261
Deferred income tax expense (benefit)	20,647	(46,608)
Change in accrued expenses and other liabilities, net	(22,500)	70,342
Income from bank owned life insurance, net	(3,388)	(2,119)
Amortization of intangible assets	8,144	8,029
Change in accrued interest receivable and other assets, net	47,069	(46,134)
Net cash provided by operating activities	170,421	97,823
Cash flows from investing activities:
Net decrease in interest-bearing time deposits with financial institutions	137	0
Loan originations and payments, net	(339,184)	(527,053)
Proceeds from loans held for sale previously classified as portfolio loans	449	38,246
Purchase of loans held for investment	0	(66,470)
Proceeds from prepayments and maturities of securities held-to-maturity	4,790	5,208
Purchase of securities available-for-sale	(1,331,037)	(458,667)
Proceeds from prepayments and maturities of securities available-for-sale	273,521	63,985
Proceeds from sale of securities available-for-sale	464,651	339,853
Proceeds from the sales of premises and equipment	13	42
Proceeds from surrender of bank-owned life insurance	1,307	0
Purchase of bank-owned life insurance	(150,000)	0
Purchases of premises and equipment	(3,102)	(1,198)
Change in FHLB, FRB, and other stock, at cost	86	(44)
Funding of CRA investments, net	(13,603)	(7,375)
Change in cash acquired in acquisitions, net	0	937,100
Net cash (used in) provided by investing activities	(1,091,972)	323,627
Cash flows from financing activities:
Net increase in deposit accounts	800,920	1,162,194
Net change in short-term borrowings	(10,000)	(681,000)
Repayment of long-term FHLB borrowings	(21,503)	(5,000)
Proceeds from issuance of subordinated debt, net	0	147,359
Redemption of junior subordinated debt securities	(25,750)	0
Cash dividends paid	(59,521)	(29,874)
Repurchase and retirement of common stock	(6,897)	0
Proceeds from exercise of stock options	732	1,024
Restricted stock surrendered and canceled	(5,308)	(1,273)
Net cash provided by financing activities	672,673	593,430
Net (decrease) increase in cash and cash equivalents	(248,878)	1,014,880
Cash and cash equivalents, beginning of period	880,766	326,850
Cash and cash equivalents, end of period	631,888	1,341,730
Supplemental cash flow disclosures:
Interest paid	21,614	28,057
Income taxes paid	35,211	125
Noncash investing activities during the period:
Transfers from portfolio loans to loans held for sale	0	42,169
Recognition of operating lease right-of-use assets	0	(11,118)
Recognition of operating lease liabilities	0	11,118
Receivable on unsettled security sales	0	6,529
Due on unsettled security purchases	(12,830)	(33,960)
Fair value of stock and equity award consideration	0	749,603
Cash consideration	0	2
Fair value of assets acquired	0	8,097,225
Liabilities assumed	$ 0	$ 7,347,620