Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]
Balance at Dec. 31, 2016	$ 387,098	$ 203	$ (6,632)	$ 213,078	$ 182,190	$ (1,741)
Net income	24,346	0	0	0	24,346	0
Other comprehensive income	2,070	0	0	0	0	2,070
Total comprehensive income	26,416	0	0	0	24,346	2,070
Cash dividends paid on common shares	5,163	0	0	0	5,163	0
Issuance under equity compensation plans, net	(2,903)	1	0	(2,904)	0	0
Share-based Compensation	1,576	0	0	1,576	0	0
Shares issued in connection with acquisition	141,729	33	0	141,696	0	0
Reclassification for the adoption of new accounting standards	0	0	0	(5,229)	5,229	0
Balance at Jun. 30, 2017	548,753	237	(6,632)	348,217	206,602	329
Balance at Dec. 31, 2017	548,573	238	(23,268)	350,061	225,360	(3,818)
Net income	43,172	0	0	0	43,172	0
Other comprehensive income	(7,928)	0	0	0	0	(7,928)
Total comprehensive income	35,244	0	0	0	43,172	(7,928)
Cash dividends paid on common shares	5,086	0	0	0	5,086	0
Repurchase of common stock	3,058	0	3,058	0	0	0
Issuance under equity compensation plans, net	(3,220)	1	0	(3,221)	0	0
Share-based Compensation	1,631	0	0	1,631	0	0
Reclassification for the adoption of new accounting standards	0	0	0	0	834	(834)
Balance at Jun. 30, 2018	$ 574,084	$ 239	$ (26,326)	$ 348,471	$ 264,280	$ (12,580)