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	$ 35,299,000	$ 40,461,000	$ 35,331,000
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of discounts and premiums on securities	3,747,000	2,590,000	3,788,000
Gain on sale of securities available-for-sale	(277,000)	(661,000)	(266,000)
Gain on sale of SBA loans	(839,000)	(689,000)	(698,000)
Proceeds from sale of SBA loans originated for sale	11,154,000	10,096,000	11,765,000
SBA loans originated for sale	(10,962,000)	(8,504,000)	(15,214,000)
Provision for credit losses on loans	13,233,000	846,000	7,421,000
Increase in cash surrender value of life insurance	(1,845,000)	(1,404,000)	(1,045,000)
Depreciation and amortization	951,000	846,000	753,000
Amortization of other intangible assets	3,751,000	2,739,000	1,943,000
Stock option expense, net	559,000	640,000	708,000
Amortization of restricted stock awards, net	1,689,000	1,283,000	1,109,000
Amortization of subordinated debt issuance costs	186,000	185,000	186,000
Gain on proceeds from company owned life insurance	(20,000)
Effect of changes in:
Accrued interest receivable and other assets	8,101,000	8,407,000	1,572,000
Accrued interest payable and other liabilities	(6,641,000)	(6,492,000)	1,219,000
Net cash provided by operating activities	58,086,000	50,343,000	48,572,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of securities available-for-sale		(111,954,000)	(162,806,000)
Purchase of securities held-to-maturity	(30,916,000)	(50,041,000)	(31,496,000)
Maturities/paydowns/calls of securities available-for-sale	114,662,000	53,566,000	57,142,000
Maturities/paydowns/calls of securities held-to-maturity	97,365,000	59,361,000	50,773,000
Proceeds from sales of securities available-for-sale	56,598,000	167,551,000	94,291,000
Net change in loans	(85,646,000)	33,810,000	38,394,000
Changes in Federal Home Loan Bank stock and other investments	(3,680,000)	1,161,000	(4,483,000)
Purchase of premises and equipment	(3,160,000)	(203,000)	(187,000)
Cash received in bank acquisition, net of cash paid		117,988,000	36,028,000
Proceeds from redemption of company-owned life insurance	369,000
Net cash provided by investing activities	145,592,000	271,239,000	77,656,000
CASH FLOWS FROM FINANCING ACTIVITIES:
Net change in deposits	499,718,000	2,977,000	(262,085,000)
Redemption of subordinated debt		(10,000,000)
Payment for early debt extinguishment penalty		(300,000)
Net change in short-term borrowings	(328,000)	(114,000)
Exercise of stock options	1,714,000	1,626,000	2,667,000
Common stock offering costs		(246,000)
Payment of cash dividends	(31,079,000)	(22,723,000)	(18,464,000)
Net cash provided by (used in) financing activities	470,025,000	(28,780,000)	(277,882,000)
Net increase in cash and cash equivalents	673,703,000	292,802,000	(151,654,000)
Cash and cash equivalents, beginning of period	457,370,000	164,568,000	316,222,000
Cash and cash equivalents, end of period	1,131,073,000	457,370,000	164,568,000
Supplemental disclosures of cash flow information:
Interest paid	8,558,000	9,935,000	7,528,000
Income taxes paid, net	10,640,000	17,730,000	12,838,000
Supplemental schedule of non-cash activity:
Recording of right to use assets in exchange for lease obligations	$ 26,654,000	9,566,000
Transfer of loans held-for-sale to loan portfolio		$ 694,000	$ 4,917,000