CONDENSED CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2017	$ 294,265	$ 177,458	$ 167,852	$ (18,685)	$ (32,360)
Balance, shares at Dec. 31, 2017		49,800,126
Net income	8,556		8,556
Other comprehensive income (loss)	(3,990)			(3,990)
Stock option exercises, value	229	$ (284)			513
Stock option exercises, shares		68,801
Stock option expense	13	$ 13
Restricted stock grants, value		$ (207)			207
Restricted stock grants, shares		27,702
Restricted stock forfeitures, shares		(807)
Restricted stock expense	242	$ 248			(6)
Vesting of Long-term Incentive Plan, value	344	$ 69			275
Vesting of Long-term Incentive Plan, shares		36,871
Cash dividend payments	(2,989)		(2,989)
Treasury stock purchases, value	(475)				(475)
Treasury stock purchases, shares		(50,202)
Balance at Mar. 31, 2018	296,195	$ 177,297	173,419	(22,675)	(31,846)
Balance, shares at Mar. 31, 2018		49,882,491
Balance at Dec. 31, 2017	294,265	$ 177,458	167,852	(18,685)	(32,360)
Balance, shares at Dec. 31, 2017		49,800,126
Net income	27,626
Other comprehensive income (loss)	(7,098)
Balance at Sep. 30, 2018	306,043	$ 177,412	186,000	(25,783)	(31,586)
Balance, shares at Sep. 30, 2018		49,922,514
Balance at Mar. 31, 2018	296,195	$ 177,297	173,419	(22,675)	(31,846)
Balance, shares at Mar. 31, 2018		49,882,491
Net income	9,541		9,541
Other comprehensive income (loss)	(1,402)			(1,402)
Stock option exercises, value	3	$ (8)			11
Stock option exercises, shares		1,300
Stock option expense	19	$ 19
Restricted stock grants, value		$ (226)			226
Restricted stock grants, shares		30,283
Restricted stock expense	229	$ 229
Cash dividend payments	(2,995)		(2,995)
Treasury stock purchases, value	(106)				(106)
Treasury stock purchases, shares		(10,000)
Balance at Jun. 30, 2018	301,484	$ 177,311	179,965	(24,077)	(31,715)
Balance, shares at Jun. 30, 2018		49,904,074
Net income	9,529		9,529
Other comprehensive income (loss)	(1,706)			(1,706)
Stock option expense	19	$ 19
Restricted stock grants, value		$ (191)			191
Restricted stock grants, shares		25,422
Restricted stock forfeitures, shares		(3,792)
Restricted stock expense	243	$ 273			(30)
Cash dividend payments	(3,494)		(3,494)
Treasury stock purchases, value	(32)				(32)
Treasury stock purchases, shares		(3,190)
Balance at Sep. 30, 2018	306,043	$ 177,412	186,000	(25,783)	(31,586)
Balance, shares at Sep. 30, 2018		49,922,514
Balance at Dec. 31, 2018	309,334	$ 177,492	192,062	(21,436)	(38,784)
Balance, shares at Dec. 31, 2018		49,128,875
Net income	8,656		8,656
Other comprehensive income (loss)	3,020			3,020
Stock option exercises, value	70	$ (187)			257
Stock option exercises, shares		33,000
Stock option expense	6	$ 6
Restricted stock grants, value		$ (148)			148
Restricted stock grants, shares		18,969
Restricted stock forfeitures, value		$ 6			(6)
Restricted stock forfeitures, shares		(834)
Restricted stock expense	143	$ 143
Vesting of Long-term Incentive Plan, value	523	$ 98			425
Vesting of Long-term Incentive Plan, shares		54,463
Cash dividend payments	(3,432)		(3,432)
Treasury stock purchases, value	(3,611)				(3,611)
Treasury stock purchases, shares		(381,785)
Balance at Mar. 31, 2019	314,709	$ 177,410	197,286	(18,416)	(41,571)
Balance, shares at Mar. 31, 2019		48,852,688
Balance at Dec. 31, 2018	309,334	$ 177,492	192,062	(21,436)	(38,784)
Balance, shares at Dec. 31, 2018		49,128,875
Net income	29,646
Other comprehensive income (loss)	$ 8,763
Stock option exercises, shares	64,200
Balance at Sep. 30, 2019	$ 326,856	$ 177,314	211,012	(12,673)	(48,797)
Balance, shares at Sep. 30, 2019		48,087,430
Balance at Mar. 31, 2019	314,709	$ 177,410	197,286	(18,416)	(41,571)
Balance, shares at Mar. 31, 2019		48,852,688
Net income	10,486		10,486
Other comprehensive income (loss)	3,236			3,236
Stock option exercises, value	52	$ (157)			209
Stock option exercises, shares		26,600
Restricted stock grants, value		$ (90)			90
Restricted stock grants, shares		11,489
Restricted stock expense	156	$ 156
Cash dividend payments	(3,417)		(3,417)
Treasury stock purchases, value	(7,668)				(7,668)
Treasury stock purchases, shares		(821,987)
Balance at Jun. 30, 2019	317,554	$ 177,319	204,355	(15,180)	(48,940)
Balance, shares at Jun. 30, 2019		48,068,790
Net income	10,504		10,504
Other comprehensive income (loss)	2,507			2,507
Stock option exercises, value	8	$ (28)			36
Stock option exercises, shares		4,600
Restricted stock grants, value		$ (138)			138
Restricted stock grants, shares		17,049
Restricted stock expense	161	$ 161
Cash dividend payments	(3,847)		(3,847)
Treasury stock purchases, value	(31)				(31)
Treasury stock purchases, shares		(3,009)
Balance at Sep. 30, 2019	$ 326,856	$ 177,314	$ 211,012	$ (12,673)	$ (48,797)
Balance, shares at Sep. 30, 2019		48,087,430