CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Cash flows from operating activities:
Net income	$ 25,740	$ 41,098	$ 38,718
Adjustments to net income:
Depreciation and amortization expense	2,580		2,259
Provision for credit losses	25,454	2,297	1,526
Share-based compensation expense	2,309		2,453
Loss on sales and disposals of premises and equipment	10		64
Net amortization on securities	1,238		1,453
Net accretion of discounts/premiums for acquired loans and deferred loan fees/costs	(5,604)		(5,723)
Gain on sales of investment securities available-for-sale	(7,760)		(427)
Originations of loans held for sale	(10,491)		(31,762)
Proceeds from the sales of and principal payments from loans held for sale	13,961		27,623
Gain on sales of loans	(771)		(1,729)
Deferred income tax (benefit) expense	(7,476)		1,995
Change in accrued expenses and other liabilities, net	(5,058)		(11,956)
Income from bank owned life insurance, net	(1,129)		(713)
Amortization of core deposit intangible	3,965		4,436
Change in accrued interest receivable and other assets, net	8,953		13,091
Net cash provided by operating activities	45,921		41,308
Cash flows from investing activities:
Net decrease in interest-bearing time deposits with financial institutions	0		247
Loan originations and payments, net	11,902		(23,660)
Proceeds from loans held for sale previously classified as portfolio loans	25,038		0
Purchase of loans held for investment	(66,470)		0
Proceeds from prepayments and maturities of held-to-maturity securities	3,234		1,310
Purchase of securities available-for-sale	(104,725)		(226,836)
Proceeds from prepayments and maturities of securities available-for-sale	18,737		28,404
Proceeds from sale of securities available-for-sale	97,886		168,837
Proceeds from the sales of premises and equipment	38		2,650
Proceeds from bank owned insurance death benefit	0		220
Purchases of premises and equipment	(5,242)		(1,805)
Change in FHLB, FRB and other stock, at cost	(8)		488
Funding of CRA investments	(2,705)		(470)
Net cash used in investing activities	(22,315)		(50,615)
Cash flows from financing activities:
Net increase in deposit accounts	194,563		56,823
Net change in short-term borrowings	9,000		(53,075)
Repayment of long-term FHLB borrowings	(5,000)		(5,000)
Cash dividends paid	(14,882)		(13,749)
Proceeds from exercise of stock options	903		331
Restricted stock surrendered and canceled	(1,008)		(1,047)
Net cash provided by (used in) financing activities	183,576		(15,717)
Net increase in cash and cash equivalents	207,182		(25,024)
Cash and cash equivalents, beginning of period	326,850		203,406
Cash and cash equivalents, end of period	534,032	$ 326,850	178,382
Supplemental cash flow disclosures:
Interest paid	13,618		18,519
Income taxes paid	84		53
Noncash investing activities during the period:
Transfers from portfolio loans to loans held for sale	26,176		0
Transfers from loans to other real estate owned	0		34
Recognition of operating lease right-of-use assets	(10,706)		(45,675)
Recognition of operating lease liabilities	10,706		45,675
Receivable on unsettled security sales	57,385		1,061
Due on unsettled security purchases	$ 0		$ (25,657)