CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment [Member]	Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Common Stock [Member]	Common Stock [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Surplus [Member]	Surplus [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Treasury Stock [Member]	Treasury Stock [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Other Comprehensive Loss [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Balance at Dec. 31, 2018	$ 469,013	$ 661	$ 469,674	$ 16,459	$ 16,459	$ 309,088	$ 309,088	$ (8,988)	$ (8,988)	$ 154,799	$ 661	$ 155,460	$ (2,345)	$ (2,345)
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201602Member
Net income	$ 35,201									35,201
Other comprehensive income (loss)	516												516
Restricted stock units issued				109		(109)
Restricted stock units/awards repurchased on vesting to pay taxes	(981)			(30)		(951)
Amortization of restricted stock awards/units	4,374					4,374
Cash dividends declared on common stock	(2,913)									(2,913)
Share repurchase	(16,717)							(16,717)
Common stock options exercised	23			1		22
Exercise of warrants				2		(2)
Issuance of shares for Employee Stock Purchase Plan	532			15		517
Issuance of common stock for acquisitions	5,641			117		5,524
Balance at Sep. 30, 2019	495,350			16,673		318,463		(25,705)		187,748			(1,829)
Balance at Jun. 30, 2019	493,888			16,557		311,428		(8,988)		176,495			(1,604)
Net income	12,226									12,226
Other comprehensive income (loss)	(225)												(225)
Amortization of restricted stock awards/units	1,509					1,509
Cash dividends declared on common stock	(973)									(973)
Share repurchase	(16,717)							(16,717)
Common stock options exercised	1					1
Issuance of common stock for acquisitions	5,641			116		5,525
Balance at Sep. 30, 2019	495,350			16,673		318,463		(25,705)		187,748			(1,829)
Balance at Dec. 31, 2019	503,652			16,733		319,375		(29,990)		199,029			(1,495)
Net income	23,162									23,162
Other comprehensive income (loss)	(252)												(252)
Restricted stock units issued				131		(131)
Restricted stock units/awards repurchased on vesting to pay taxes	(643)			(33)		(610)
Amortization of restricted stock awards/units	5,062					5,062
Cash dividends declared on common stock	(2,832)									(2,832)
Share repurchase	(6,487)							(6,487)
Common stock options exercised	76			7		69
Exercise of warrants				6		(6)
Issuance of shares for Employee Stock Purchase Plan	990			43		947
Issuance of common stock for acquisitions				29		(29)
Balance at Sep. 30, 2020	522,728			16,916		324,677		(36,477)		219,359			(1,747)
Balance at Jun. 30, 2020	507,980			16,900		322,796		(36,477)		206,757			(1,996)
Net income	13,547									13,547
Other comprehensive income (loss)	249												249
Amortization of restricted stock awards/units	1,798					1,798
Cash dividends declared on common stock	(945)									(945)
Issuance of shares for Employee Stock Purchase Plan	99			4		95
Issuance of common stock for acquisitions				12		(12)
Balance at Sep. 30, 2020	$ 522,728			$ 16,916		$ 324,677		$ (36,477)		$ 219,359			$ (1,747)