Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock Outstanding [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings (Deficit) [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Loss [Member]
Balance, beginning at Dec. 31, 2016	$ (72,114)		$ 416	$ 130,189	$ (125,825)	$ (90,918)	$ 14,024
Balance, Shares beginning at Dec. 31, 2016		35,048,338
Stock-based compensation	1,179			1,179
Exercise of stock options	2,525		4	2,521
Exercise of stock options, Shares		360,211
Settlement of restricted stock units			4	(4)
Settlement of restricted stock units, Shares		397,522
Acquisition of treasury stock	$ (11,401)					(11,401)
Acquisition of treasury stock, Shares	(1,795,444)	(1,795,444)
Other comprehensive income, net	$ (26,358)						(26,358)
Net income (loss)	35,679				35,679
Balance, ending at Jun. 30, 2017	(70,490)		424	133,885	(90,146)	(102,319)	(12,334)
Balance, Shares ending at Jun. 30, 2017		34,010,627
Balance, beginning at Mar. 31, 2017							(19,294)
Other comprehensive income, net	6,960						6,960
Net income (loss)	(8,059)
Balance, ending at Jun. 30, 2017	(70,490)		424	133,885	(90,146)	(102,319)	(12,334)
Balance, Shares ending at Jun. 30, 2017		34,010,627
Balance, beginning at Dec. 31, 2017	(39,637)		426	136,259	(40,889)	(102,319)	(33,114)
Impact of adopting the new revenue standard at Dec. 31, 2017	8,484				8,484
Balance as adjusted, beginning at Dec. 31, 2017	$ (31,153)		426	136,259	(32,405)	(102,319)	(33,114)
Balance, Shares beginning at Dec. 31, 2017	34,189,599	34,189,599
Stock-based compensation	$ 2,810			2,810
Exercise of stock options	436		1	435
Exercise of stock options, Shares		64,753
Settlement of restricted stock units			2	(2)
Settlement of restricted stock units, Shares		248,834
Acquisition of treasury stock	(199)					(199)
Acquisition of treasury stock, Shares		(19,432)
Other comprehensive income, net	13,055						13,055
Net income (loss)	(18,742)				(18,742)
Balance, ending at Jun. 30, 2018	$ (33,793)		429	139,502	(51,147)	(102,518)	(20,059)
Balance, Shares ending at Jun. 30, 2018	34,483,754	34,483,754
Balance, beginning at Mar. 31, 2018							(36,270)
Other comprehensive income, net	$ 16,211						16,211
Net income (loss)	(21,505)
Balance, ending at Jun. 30, 2018	$ (33,793)		$ 429	$ 139,502	$ (51,147)	$ (102,518)	$ (20,059)
Balance, Shares ending at Jun. 30, 2018	34,483,754	34,483,754