Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
OPERATING ACTIVITIES
Net income	$ 122,044	$ 158,873	$ 143,112
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of premises and equipment	14,131	11,567	10,451
Other net (accretion) amortization	(9,890)	996	3,932
Provision for credit losses	107,741	11,198	7,764
Net securities (gains) losses	(4,268)	(4,320)	900
Mortgage banking income	(22,736)	(8,219)	(5,840)
Stock compensation expense	5,653	5,321	4,361
(Increase) decrease in deferred income tax assets, net	(10,518)	8,466	7,163
Increase in cash surrender value of bank-owned life insurance	(7,359)	(5,913)	(6,427)
Contribution to pension plan		(3,000)	(2,700)
Loans originated for sale	(910,155)	(328,319)	(215,540)
Proceeds from the sale of loans originated for sale	786,352	308,856	227,100
Net change in equity securities	344	(104)	(700)
Net change in: accrued interest receivable and other assets	(30,280)	(33,400)	19,895
Net change in: accrued interest payable and other liabilities	16,189	41,500	(1,347)
Other—net	2,358	(139)	(233)
Net cash provided by operating activities	59,606	163,363	191,891
INVESTING ACTIVITIES
Net (increase) decrease in loans held for investment	(538,688)	(61,804)	121,504
Available-for-sale debt securities:
Proceeds from sales	226,099	125,839	82,134
Proceeds from maturities, prepayments and calls	803,006	438,259	267,936
Purchases of securities	(585,930)	(573,729)	(841,696)
Held-to-maturity debt securities:
Proceeds from maturities, prepayments and calls	200,100	163,667	78,938
Purchases of securities	(82,695)	(41,516)	(89,933)
Equity securities:
Proceeds from sales	203	4,090	1,511
Net cash received from business acquisitions		60,025	278,654
Proceeds from bank owned life insurance	832	1,156	4,772
Purchases of premises and equipment—net	(7,551)	(12,201)	(4,669)
Sale of portfolio loans	42,416		48,990
Net cash provided by (used in) investing activities	57,792	103,786	(51,859)
FINANCING ACTIVITIES
Increase (decrease) in deposits	1,435,497	(199,771)	(129,878)
Proceeds from Federal Home Loan Bank borrowings	475,000	1,035,000	640,000
Repayment of Federal Home Loan Bank borrowings	(1,341,814)	(888,862)	(589,546)
(Decrease) increase in other short-term borrowings	(32,912)	(44,788)	86,284
Principal repayments of finance lease obligations	(422)	(402)	(334)
(Decrease) increase in federal funds purchased	(7,500)	7,500	(25,000)
Repayment of junior subordinated debt	(6,702)	(33,506)	(17,519)
Dividends paid to common shareholders	(85,253)	(66,571)	(53,577)
Dividends paid to preferred shareholders	(2,644)
Issuance of common stock	59	72	1,578
Issuance of preferred stock, net of issuance costs	144,484
Treasury shares purchased—net	(24,540)	(10,211)	(426)
Net cash provided by (used in) financing activities	553,253	(201,539)	(88,418)
Net increase in cash, cash equivalents and restricted cash	670,651	65,610	51,614
Cash, cash equivalents and restricted cash at beginning of the year	234,796	169,186	117,572
Cash, cash equivalents and restricted cash at end of the year	905,447	234,796	169,186
SUPPLEMENTAL DISCLOSURES
Interest paid on deposits and other borrowings	75,082	87,145	68,618
Income taxes paid	36,975	31,375	18,700
Transfers of loans to other real estate owned	263	1,015	1,275
Transfers of portfolio loans to loans held for sale	$ 42,416		48,990
Non-cash transactions related to OLBK, FFKT and FTSB acquisitions		493,935	$ 498,614
Transfers of held-to-maturity debt securities to available-for-sale debt securities		67,393
Right of use assets obtained in exchange for lease obligations		$ 19,827