Condensed Consolidated Statements of Changes in Shareholders Equity (Unaudited) - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total
Beginning balance at Dec. 31, 2017	$ 257	$ 343,249	$ 118,353	$ (15,256)	$ (389)	$ 446,214
Beginning balance, shares at Dec. 31, 2017	25,731,504			(898,272)
Net income			20,154			20,154
Dividends on common stock, $0.10 and $0.05 and $0.20 and $0.10 per share for the three months ended and six months ended June 30, 2019 and 2018 respectively			(2,507)			(2,507)
Exercise of stock options		(181)		$ 431		250
Exercise of stock options (in shares)				25,400
Stock-based compensation expense		739				739
Other comprehensive income (loss), net of tax					(3,655)	(3,655)
Ending balance at Jun. 30, 2018	$ 257	343,807	136,000	$ (14,825)	(4,044)	461,195
Ending balance, shares at Jun. 30, 2018	25,731,504			(872,872)
Beginning balance at Mar. 31, 2018	$ 257	343,641	126,213	$ (15,256)	(3,284)	451,571
Beginning balance, shares at Mar. 31, 2018	25,731,504			(898,272)
Net income			11,042			11,042
Dividends on common stock, $0.10 and $0.05 and $0.20 and $0.10 per share for the three months ended and six months ended June 30, 2019 and 2018 respectively			(1,255)			(1,255)
Exercise of stock options		(181)		$ 431		250
Exercise of stock options (in shares)				25,400
Stock-based compensation expense		347				347
Other comprehensive income (loss), net of tax					(760)	(760)
Ending balance at Jun. 30, 2018	$ 257	343,807	136,000	$ (14,825)	(4,044)	461,195
Ending balance, shares at Jun. 30, 2018	25,731,504			(872,872)
Beginning balance at Dec. 31, 2018	$ 258	344,497	160,626	$ (14,781)	(2,975)	487,625
Beginning balance, shares at Dec. 31, 2018	25,777,693			(870,272)
Net income			24,805			24,805
Dividends on common stock, $0.10 and $0.05 and $0.20 and $0.10 per share for the three months ended and six months ended June 30, 2019 and 2018 respectively			(5,030)			(5,030)
Vesting of restricted stock, net of shares withheld for employee tax liabilities		(19)				(19)
Vesting of restricted stock, net of shares withheld for employee tax liabilities (in shares)	2,442
Exercise of stock options, net of shares withheld for employee tax liabilities		(95)		$ 217		122
Exercise of stock options, net of shares withheld for employee tax liabilities (in shares)				12,806
Stock-based compensation expense		1,112				1,112
Other comprehensive income (loss), net of tax					4,543	4,543
Ending balance at Jun. 30, 2019	$ 258	345,495	180,401	$ (14,564)	1,568	513,158
Ending balance, shares at Jun. 30, 2019	25,780,135			(857,466)
Beginning balance at Mar. 31, 2019	$ 258	344,971	168,603	$ (14,597)	(582)	498,653
Beginning balance, shares at Mar. 31, 2019	25,777,904			(859,428)
Net income			14,315			14,315
Dividends on common stock, $0.10 and $0.05 and $0.20 and $0.10 per share for the three months ended and six months ended June 30, 2019 and 2018 respectively			(2,517)			(2,517)
Vesting of restricted stock, net of shares withheld for employee tax liabilities		(17)				(17)
Vesting of restricted stock, net of shares withheld for employee tax liabilities (in shares)	2,231
Exercise of stock options, net of shares withheld for employee tax liabilities		(26)		$ 33		7
Exercise of stock options, net of shares withheld for employee tax liabilities (in shares)				1,962
Stock-based compensation expense		567				567
Other comprehensive income (loss), net of tax					2,150	2,150
Ending balance at Jun. 30, 2019	$ 258	$ 345,495	$ 180,401	$ (14,564)	$ 1,568	$ 513,158
Ending balance, shares at Jun. 30, 2019	25,780,135			(857,466)