CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 159,718	$ 123,340	$ 60,100
Adjustments to net income:
Depreciation and amortization expense	9,815	7,773	4,888
Provision for credit losses	5,719	8,253	8,432
Share-based compensation expense	10,528	9,033	5,809
(Gain) loss on sale and disposal of premises and equipment	(42)	108	234
Gain on sale of or write down of other real estate owned	(55)	(355)	(46)
Net amortization on securities	4,745	6,900	7,601
Net accretion of discounts/premiums for acquired loans and deferred loan fees/costs	(27,378)	(21,401)	(16,172)
Gain on sale of investment securities available-for-sale	(8,571)	(1,399)	(2,737)
Originations of loans held for sale	(98,232)	(147,740)	(135,348)
Proceeds from the sales of and principal payments from loans held for sale	111,952	184,220	132,320
Gain on sale of loans	(6,642)	(10,759)	(12,468)
Deferred income tax expense	7,496	9,275	16,420
Change in accrued expenses and other liabilities, net	(6,265)	14,157	5,193
Income from bank owned life insurance, net	(2,689)	(2,774)	(1,842)
Amortization of core deposit intangible	17,245	13,594	6,144
Change in accrued interest receivable and other assets, net	5,346	4,266	(9,157)
Net cash provided by (used) in operating activities	182,690	196,491	69,371
Cash flows from investing activities:
Net increase in interest-bearing time deposits with financial institutions	3,435	490	(2,689)
Proceeds from sale of other real estate owned	405	1,058	507
Loan originations and payments, net	266,632	(340,023)	(601,617)
Proceeds from loans held for sale previously classified as portfolio loans	86,313	125,485	103,049
Purchase of loans held for investment	(222,701)	(61,562)	(13,582)
Purchase of held-to-maturity securities	0	(29,002)	(10,914)
Proceeds from prepayments and maturities of held-to-maturity securities	7,318	1,785	1,166
Purchase of securities available-for-sale	(889,516)	(462,534)	(306,527)
Proceeds from prepayments and maturities of securities available-for-sale	114,520	131,268	74,891
Proceeds from sale or maturity of securities available-for-sale	551,784	407,004	268,596
Proceeds from the sale of premises and equipment	14,751	0	18
Proceeds from bank owned insurance death benefit	405	1,284	198
Purchases of premises and equipment	(18,834)	(10,295)	(4,183)
Change in FHLB, FRB, and other stock, at cost	2,306	(27,086)	(12,838)
Funding of CRA investments	(15,069)	(21,936)	(6,189)
Cash acquired in acquisitions, net	0	146,571	225,945
Net cash used in investing activities	(98,251)	(137,493)	(284,169)
Cash flows from financing activities:
Net increase in deposit accounts	240,158	65,553	187,901
Net change in short-term borrowings	(115,075)	(108,064)	61,120
Proceeds from FHLB borrowings	0	0	12,012
Repayment of FHLB borrowings	(35,500)	(10,500)	(9,262)
Redemption of junior subordinated debt securities	(18,558)	0	0
Proceeds from issuance of subordinated debt, net	122,453	0	0
Cash dividends paid	(53,867)	0	0
Repurchase and retirement of common stock	(100,000)	0	0
Proceeds from exercise of stock options	2,679	1,924	4,592
Restricted stock surrendered and canceled	(3,285)	(1,669)	(1,258)
Net cash provided by (used in) financing activities	39,005	(52,756)	255,105
Net change in cash and cash equivalents	123,444	6,242	40,307
Cash and cash equivalents, beginning of year	203,406	197,164	156,857
Cash and cash equivalents, end of year	326,850	203,406	197,164
Supplemental cash flow disclosures:
Interest paid	79,386	53,960	21,777
Income taxes paid	52,093	32,296	18,846
Noncash investing activities:
Loans held for sale transfer to loans held for investment	89,259	133,499	99,066
Transfers from loans to other real estate owned	644	15	121
Recognition of operating lease right-of-use assets	(52,701)	0	0
Recognition of operating lease liabilities	52,701	0	0
Assets acquired (liabilities assumed) in acquisitions (See Note 27):
Investment securities	0	392,858	442,923
Loans	0	2,352,717	2,427,589
Core deposit intangible	0	71,943	39,703
Deferred income tax	0	4,383	14,959
Goodwill	0	313,043	391,070
Fixed assets	0	9,122	42,097
Other assets	0	97,246	74,379
Deposits	0	(2,506,929)	(2,752,501)
Other borrowings	0	(254,923)	(180,186)
Other liabilities	0	(24,859)	(16,395)
Common Stock and additional paid-in capital	$ 0	$ (601,172)	$ (716,421)