Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING ACTIVITIES
Net income	$ 158,873	$ 143,112	$ 94,482
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of premises and equipment	11,567	10,451	10,441
Other net amortization	996	3,932	8,871
Provision for credit losses	11,198	7,764	9,986
Net securities (gains) losses	(4,320)	900	(567)
Mortgage banking income	(8,219)	(5,840)	(5,053)
Stock compensation expense	5,321	4,361	2,956
Decrease in deferred income tax assets, net	8,466	7,163	27,112
Increase in cash surrender value of bank-owned life insurance	(5,913)	(6,427)	(4,794)
Contribution to pension plan	(3,000)	(2,700)	(5,000)
Loans originated for sale	(328,319)	(215,540)	(216,744)
Proceeds from the sale of loans originated for sale	308,856	227,100	213,610
Net change in equity securities	(104)	(700)	(773)
Net change in: accrued interest receivable and other assets	(33,400)	19,895	4,593
Net change in: accrued interest payable and other liabilities	41,500	(1,347)	3,398
Other—net	(139)	(233)	(438)
Net cash provided by operating activities	163,363	191,891	142,080
INVESTING ACTIVITIES
Net (increase) decrease in loans held for investment	(61,804)	121,504	(90,225)
Available-for-sale debt securities:
Proceeds from sales	125,839	82,134	7,760
Proceeds from maturities, prepayments and calls	438,259	267,936	211,383
Purchases of securities	(573,729)	(841,696)	(252,114)
Held-to-maturity debt securities:
Proceeds from maturities, prepayments and calls	163,667	78,938	118,180
Purchases of securities	(41,516)	(89,933)	(66,473)
Equity securities:
Proceeds from sales	4,090	1,511
Purchases of securities			(200)
Net cash received from business acquisitions	60,025	278,654
Proceeds from bank-owned life insurance	1,156	4,772	349
Purchases of premises and equipment—net	(12,201)	(4,669)	(6,035)
Sale of portfolio loans—net		48,990
Net cash provided by (used in) investing activities	103,786	(51,859)	(77,375)
FINANCING ACTIVITIES
(Decrease) increase in deposits	(199,771)	(129,878)	4,262
Proceeds from Federal Home Loan Bank borrowings	1,035,000	640,000	680,000
Repayment of Federal Home Loan Bank borrowings	(888,862)	(589,546)	(700,716)
(Decrease) increase in other short-term borrowings	(44,788)	86,284	18,429
Principal repayments of finance lease obligations	(402)	(334)	(454)
Increase (decrease) in federal funds purchased	7,500	(25,000)	(33,000)
Repayment of junior subordinated debt	(33,506)	(17,519)
Dividends paid to common shareholders	(66,571)	(53,577)	(44,864)
Issuance of common stock	72	1,578	1,040
Treasury shares purchased—net	(10,211)	(426)
Net cash used in financing activities	(201,539)	(88,418)	(75,303)
Net increase (decrease) in cash and cash equivalents	65,610	51,614	(10,598)
Cash and cash equivalents at beginning of the year	169,186	117,572	128,170
Cash and cash equivalents at end of the year	234,796	169,186	117,572
SUPPLEMENTAL DISCLOSURES
Interest paid on deposits and other borrowings	87,145	68,618	42,534
Income taxes paid	31,375	18,700	22,875
Transfers of loans to other real estate owned	1,015	1,275	$ 635
Transfers of portfolio loans to loans held for sale		48,990
Non-cash transactions related to OLBK, FFKT and FTSB acquisitions	493,935	$ 498,614
Transfer of held-to-maturity debt securities to available-for-sale debt securities	67,393
Right of use assets obtained for exchange of lease obligations	$ 19,827