CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Cash flows from operating activities:
Net income	$ 68,668	$ 67,136	$ 25,740
Adjustments to net income:
Depreciation and amortization expense	4,009		2,580
Provision for credit losses	1,974	1,517	25,454
Share-based compensation expense	3,105		2,309
Loss on sales and disposals of premises and equipment	7		10
Net amortization on securities	5,983		1,238
Net (accretion) of discounts/premiums for acquired loans and deferred loan fees/costs	(10,833)		(5,604)
Gain on sales of investment securities available-for-sale	(4,046)		(7,760)
Loss on debt extinguishment	503		0
Originations of loans held for sale	(7,768)		(10,491)
Proceeds from the sales of and principal payments from loans held for sale	970		13,961
Gain on sales of loans	(361)		(771)
Deferred income tax expense (benefit)	14,650		(7,476)
Change in accrued expenses and other liabilities, net	(34,203)		(5,058)
Income from bank owned life insurance, net	(1,675)		(1,129)
Amortization of intangible assets	4,143	4,505	3,965
Change in accrued interest receivable and other assets, net	60,176		8,953
Net cash provided by operating activities	105,302		45,921
Cash flows from investing activities:
Net decrease in interest-bearing time deposits with financial institutions	137		0
Loan originations and payments, net	128,540		11,902
Proceeds from loans held for sale previously classified as portfolio loans	449		25,038
Purchase of loans held for investment	0		(66,470)
Proceeds from prepayments and maturities of securities held-to-maturity	1,807		3,234
Purchase of securities available-for-sale	(364,542)		(104,725)
Proceeds from prepayments and maturities of securities available-for-sale	162,568		18,737
Proceeds from sale of securities available-for-sale	179,386		97,886
Proceeds from the sales of premises and equipment	4		38
Proceeds from bank owned life insurance settlements	1,307		0
Purchases of premises and equipment	(1,465)		(5,242)
Change in FHLB, FRB, and other stock, at cost	(202)		(8)
Funding of CRA investments, net	(3,873)		(2,705)
Net cash provided by (used in) investing activities	104,116		(22,315)
Cash flows from financing activities:
Net increase in deposit accounts	525,830		194,563
Net change in short-term borrowings	0		9,000
Repayment of long-term FHLB borrowings	(21,503)		(5,000)
Cash dividends paid	(28,287)		(14,882)
Repurchase and retirement of common stock	(6,897)		0
Proceeds from exercise of stock options	620		903
Restricted stock surrendered and canceled	(5,279)		(1,008)
Net cash provided by financing activities	464,484		183,576
Net increase in cash and cash equivalents	673,902		207,182
Cash and cash equivalents, beginning of period	880,766		326,850
Cash and cash equivalents, end of period	1,554,668	$ 880,766	534,032
Supplemental cash flow disclosures:
Interest paid	10,890		13,618
Income taxes paid	77		84
Noncash investing activities during the period:
Transfers from portfolio loans to loans held for sale	0		26,176
Recognition of operating lease right-of-use assets	0		(10,706)
Recognition of operating lease liabilities	0		10,706
Receivable on unsettled security sales	0		57,385
Due on unsettled security purchases	$ (11,286)		$ 0