Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows from Operating Activities:
Net income	$ 57,518,000	$ 70,672,000	$ 63,401,000
Adjustments to reconcile net income to net cash provided by operating activities:
Net (accretion) amortization of premiums, discounts and deferred loan fees and costs	(728,000)	3,660,000	4,153,000
Depreciation and amortization	3,858,000	1,645,000	5,555,000
Amortization of intangible assets	1,025,000	1,182,000	594,000
Amortization of operating lease right-of-use assets	2,668,000	2,592,000
Provision for loan losses	27,222,000	2,130,000	4,413,000
Stock based compensation	2,659,000	2,545,000	2,425,000
Loans originated for sale	(113,203,000)	(57,605,000)	(49,748,000)
Proceeds from sales of loans held for sale	116,933,000	59,748,000	50,420,000
Gains on sales of securities	(1,213,000)	0	0
Gains on sales of loans held for sale	(3,322,000)	(1,660,000)	(1,329,000)
Gains on proceeds from bank owned life insurance policies	0	0	(421,000)
Change in market value of equity securities	552,000	(496,000)	583,000
(Gains) losses on other real estate and other repossessed assets	(88,000)	72,000	(338,000)
Loss on sale of premises and equipment	77,000	497,000	561,000
Long-term debt prepayment penalty	4,133,000	0	0
Deferred tax (benefit) expense	(6,763,000)	2,854,000	(13,571,000)
Excess tax (deficiencies) benefits	(132,000)	189,000	318,000
(Increase) decrease in other assets	(56,639,000)	(15,986,000)	2,679,000
Increase in other liabilities	50,434,000	15,092,000	9,743,000
Net Cash Provided by Operating Activities	84,991,000	87,131,000	79,438,000
Cash Flows from Investing Activities:
Net cash acquired in acquisitions	0	13,454,000	0
Proceeds from repayments and maturities of available for sale securities	700,409,000	147,130,000	91,833,000
Proceeds from repayments and maturities of held to maturity securities	38,941,000	31,457,000	26,083,000
Proceeds from sales of equity securities	4,148,000	1,287,000	2,155,000
Proceeds from sales of available for sale securities	130,912,000	0	0
Purchase of available for sale securities	(921,343,000)	(211,503,000)	(110,370,000)
Purchase of held to maturity securities	(6,377,000)	(21,453,000)	(40,753,000)
Purchase of equity securities	(2,772,000)	(1,343,000)	(570,000)
Proceeds from redemptions of Federal Home Loan Bank stock	106,808,000	95,643,000	6,799,000
Purchases of Federal Home Loan Bank stock	(96,282,000)	(103,080,000)	(7,524,000)
Death benefit proceeds from bank owned life insurance policy	0	121,000	755,000
Net increase in loans	(876,021,000)	(252,441,000)	(310,256,000)
Proceeds from dispositions and sales of bank premises and equipment	50,000	1,827,000	697,000
Purchases of premises and equipment	(7,539,000)	(5,936,000)	(5,523,000)
Proceeds from sales of other real estate and other repossessed assets	1,044,000	860,000	4,116,000
Net Cash Used in Investing Activities:	(928,022,000)	(303,977,000)	(342,558,000)
Cash Flows from Financing Activities:
Net increase in deposits	1,162,206,000	264,279,000	252,329,000
(Decrease) increase in federal funds purchased and securities sold under agreements to repurchase	(159,098,000)	94,753,000	108,969,000
Proceeds from other borrowings	25,000,000	46,260,000	60,003,000
Repayments of other borrowings	(169,948,000)	(89,353,000)	(70,752,000)
Purchase of treasury stock	(1,452,000)	0	0
Exercise of stock options	0	313,000	307,000
Retirement of restricted stock	(501,000)	(715,000)	(763,000)
Dividends paid	(25,457,000)	(24,919,000)	(21,307,000)
Net Cash Provided by Financing Activities:	830,750,000	290,618,000	328,786,000
Net (decrease) increase in cash and cash equivalents	(12,281,000)	73,772,000	65,666,000
Cash and cash equivalents, beginning of year	282,371,000	208,599,000	142,933,000
Cash and Cash Equivalents, End of Year	270,090,000	282,371,000	208,599,000
Supplemental schedule of non-cash investing and financing activities:
Cash paid during the period for income taxes	22,486,000	15,944,000	18,614,000
Cash paid during the period for interest	42,600,000	59,949,000	38,679,000
Transfer of loans into other real estate owned	393,000	665,000	3,765,000
Initial recognition of operating lease right-of-use assets		18,651,000
Initial recognition of operating lease liabilities		20,203,000
Right-of-use asset obtained in exchange for new operating lease liabilities	1,159,000	1,748,000
Non-cash assets acquired:
Federal Home Loan Bank stock	0	1,767,000	0
Investment securities	0	22,734,000	0
Loans, including loans held for sale	0	426,118,000	0
Goodwill and other intangible assets, net	0	23,125,000	0
Other assets	0	9,304,000	0
Total non-cash assets acquired	0	483,048,000	0
Liabilities assumed:
Deposits	0	409,638,000	0
Other borrowings	0	40,957,000	0
Other liabilities	0	2,490,000	0
Total liabilities assumed	0	453,085,000	0
Common stock issued for acquisitions	$ 0	$ 43,417,000	$ 0