Consolidated Statement of Shareholders' Equity Statement - USD ($) $ in Thousands	Total	Common Stock [Member]	Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income [Member]
Balances at Dec. 31, 2017	$ 544,020	$ 460	$ 823,850	$ (262,960)	$ (17,330)
Net income	24,320			24,320
Other comprehensive income (loss)	(1,480)				(1,480)
Shares surrendered upon exercise and vesting of equity awards to cover taxes	(2,300)		(2,300)
Non-cash compensation expense	1,220		1,220
Balances at Mar. 31, 2018	565,780	460	822,770	(238,640)	(18,810)
Balances at Dec. 31, 2018	620,450	460	816,500	(179,660)	(16,850)
Net income	19,090			19,090
Other comprehensive income (loss)	3,020				3,020
Purchase of common stock	(670)		(670)
Shares surrendered upon exercise and vesting of equity awards to cover taxes	(2,620)		(2,620)
Non-cash compensation expense	1,320		1,320
Impact of accounting standards adoption	(80)			1,190	(1,270)
Balances at Mar. 31, 2019	$ 640,510	$ 460	$ 814,530	$ (159,380)	$ (15,100)