CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net (loss) income	$ (6,785)	$ 118,620
Adjustments to net income (loss):
Depreciation and amortization expense	9,186	7,007
Provision for credit losses	190,299	3,422
Share-based compensation expense	7,747	7,927
Loss (gain) on sales and disposals of premises and equipment	255	(152)
Loss (gain) on sale of or write down of other real estate owned	42	(55)
Net amortization on securities	9,417	3,591
Net (accretion) of discounts/premiums for acquired loans and deferred loan fees/costs	(28,317)	(19,982)
Gain on sales of investment securities available-for-sale	(8,880)	(4,900)
Originations of loans held for sale	(12,217)	(83,521)
Proceeds from the sales of and principal payments from loans held for sale	14,201	88,683
Gain on sales of loans	(8,281)	(4,944)
Deferred income tax (benefit) expense	(52,471)	1,365
Change in accrued expenses and other liabilities, net	19,770	(4,855)
Income from bank owned life insurance, net	(3,849)	(2,029)
Amortization of intangible assets	12,567	12,998
Change in accrued interest receivable and other assets, net	28,426	7,858
Net cash provided by operating activities	171,110	131,033
Cash flows from investing activities:
Net increase in interest-bearing time deposits with financial institutions	0	3,432
Proceeds from sale of other real estate owned	273	405
Loan originations and payments, net	(111,334)	197,995
Proceeds from loans held for sale previously classified as portfolio loans	1,283,214	76,579
Purchase of loans held for investment	(66,470)	(182,504)
Proceeds from prepayments and maturities of securities held-to-maturity	9,782	4,741
Purchase of securities available-for-sale	(2,057,690)	(603,457)
Proceeds from prepayments and maturities of securities available-for-sale	149,720	85,330
Proceeds from sale of securities available-for-sale	558,899	418,471
Proceeds from the sales of premises and equipment	42	11,139
Proceeds from bank owned insurance death benefit	17,799	405
Purchases of premises and equipment	(8,687)	(16,154)
Change in FHLB, FRB, and other stock, at cost	(22,584)	2,381
Funding of CRA investments	(9,025)	(7,295)
Change in cash acquired in acquisitions, net	937,100	0
Net cash provided by (used in) investing activities	681,039	(8,532)
Cash flows from financing activities:
Net increase in deposit accounts	516,308	200,937
Net change in short-term borrowings	(681,000)	(53,075)
Repayment of long-term FHLB borrowings	(5,000)	(10,000)
Proceeds from issuance of subordinated debt, net	147,359	122,453
Redemption of junior subordinated debt securities	0	(15,465)
Cash dividends paid	(53,464)	(40,807)
Repurchase and retirement of common stock	0	(100,000)
Proceeds from exercise of stock options	1,247	394
Restricted stock surrendered and canceled	(1,372)	(2,629)
Net cash (used in) provided by financing activities	(75,922)	101,808
Net increase in cash and cash equivalents	776,227	224,309
Cash and cash equivalents, beginning of period	326,850	203,406
Cash and cash equivalents, end of period	1,103,077	427,715
Supplemental cash flow disclosures:
Interest paid	43,188	58,591
Income taxes paid	26,151	33,469
Noncash investing activities during the period:
Transfers from portfolio loans to loans held for sale	1,276,277	78,085
Transfers from loans to other real estate owned	208	329
Recognition of operating lease right-of-use assets	(11,118)	(49,542)
Recognition of operating lease liabilities	11,118	49,542
Due on unsettled security purchases	(20,000)	(2,034)
Acquisitions (See Note 4):
Fair value of stock and equity award consideration	749,603	0
Cash consideration	2	0
Fair value of assets acquired	8,102,281	0
Liabilities assumed	$ 7,352,676	$ 0