CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net income (loss)	$ 255,058	$ (6,785)
Adjustments to net income:
Depreciation and amortization expense	12,147	9,186
Provision for credit losses	(56,228)	190,299
Share-based compensation expense	9,911	7,747
Loss on sales and disposals of premises and equipment	179	255
Loss on sales of or write downs of other real estate owned	0	42
Net amortization on securities	17,078	9,417
Net (accretion) of discounts/premiums for acquired loans and deferred loan fees/costs	(31,955)	(28,317)
Gain on sales of investment securities available-for-sale	(13,321)	(8,880)
Loss on debt extinguishment	180	0
Originations of loans held for sale	(34,902)	(12,217)
Proceeds from the sales of and principal payments from loans held for sale	29,973	14,201
Gain on sales of loans	(3,094)	(8,281)
Deferred income tax expense (benefit)	29,111	(52,471)
Change in accrued expenses and other liabilities, net	(17,404)	19,770
Income from bank-owned life insurance, net	(6,071)	(3,849)
Amortization of intangible assets	12,056	12,567
Change in accrued interest receivable and other assets, net	53,953	28,426
Net cash provided by operating activities	256,671	171,110
Cash flows from investing activities:
Net decrease in interest-bearing time deposits with financial institutions	137	0
Proceeds from sales of other real estate owned	0	273
Loan originations and payments, net	(719,657)	(111,334)
Proceeds from loans held for sale previously classified as portfolio loans	1,530	1,283,214
Purchase of loans held for investment	0	(66,470)
Proceeds from prepayments and maturities of securities held-to-maturity	7,509	9,782
Purchase of securities available-for-sale	(2,079,198)	(2,057,690)
Proceeds from prepayments and maturities of securities available-for-sale	429,235	149,720
Proceeds from sales of securities available-for-sale	630,437	558,899
Proceeds from the sales of premises and equipment	26	42
Proceeds from surrender of bank-owned life insurance	1,400	17,799
Purchase of bank-owned life insurance	(150,000)	0
Purchase of premises and equipment	(6,318)	(8,687)
Change in FHLB, FRB, and other stock, at cost	3	(22,584)
Funding of CRA investments, net	(19,001)	(9,025)
Change in cash acquired in acquisitions, net	0	937,100
Net cash (used in) provided by investing activities	(1,903,897)	681,039
Cash flows from financing activities:
Net increase in deposit accounts	1,255,822	516,308
Net change in short-term borrowings	140,000	(681,000)
Repayment of long-term FHLB borrowings	(21,503)	(5,000)
Proceeds from issuance of subordinated debt, net	0	147,359
Redemption of subordinated debentures	(171,153)	0
Cash dividends paid	(90,747)	(53,464)
Repurchase and retirement of common stock	(18,067)	0
Proceeds from exercise of stock options	782	1,247
Restricted stock surrendered and canceled	(6,354)	(1,372)
Net cash provided by (used in) financing activities	1,088,780	(75,922)
Net (decrease) increase in cash and cash equivalents	(558,446)	776,227
Cash and cash equivalents, beginning of period	880,766	326,850
Cash and cash equivalents, end of period	322,320	1,103,077
Supplemental cash flow disclosures:
Interest paid	29,745	43,188
Income taxes paid	56,472	26,151
Noncash investing activities during the period:
Transfers from portfolio loans to loans held for sale	1,006	1,276,277
Transfers from loans to other real estate owned	0	208
Transfers of investment securities from available-for-sale to held-to-maturity	154,456	0
Recognition of operating lease right-of-use assets	(3,812)	(11,118)
Recognition of operating lease liabilities	3,812	11,118
Due on unsettled security purchases	0	(20,000)
Fair value of stock and equity award consideration	0	749,603
Cash consideration	0	2
Fair value of assets acquired	0	8,102,281
Liabilities assumed	$ 0	$ 7,352,676