Condensed Consolidated Statement of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Noncontrolling Interest [Member]	Accumulated Other Comprehensive Loss
Common Stock, Dividends, Per Share, Cash Paid	$ 0.075
Beginning Balance, Issued Shares at Dec. 31, 2017		31,476,428
Beginning Balance, Value at Dec. 31, 2017		$ 3,148	$ 1,410	$ 510,975	$ 42,249	$ (24,023)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2017	$ 533,759
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	26,208			26,208
Net Income (Loss) Attributable to Noncontrolling Interest	248				248
Cumulative translation adjustment	(4,759)					(4,759)
Repurchase and retirement of common stock, Shares		(30,000)
Repurchase and retirement of common stock, Value	(2,226)	$ (3)	(1,339)	(884)
Vesting of restricted stock, Shares		13,274
Vesting of restricted stock, Value	0	$ 1	(1)
Share based compensation	753		753
Forfeiture of certain shares to satisfy exercise costs and the recipients income tax obligations related to stock options exercised and restricted stock vested, Shares		(726)
Forfeiture of certain shares to satisfy exercise costs and the recipients income tax obligations related to stock options exercised and restricted stock vested	(36)	$ 0	(36)
Recognized controlling ownership of joint venture	(389)		(787)		398
Dividends paid	(2,369)			(2,369)	0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | Calculated under Revenue Guidance in Effect before Topic 606 [Member]	(8,802)			(8,802)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | ASC 340-40 [Member]	(1,460)			(1,460)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Mar. 31, 2018	$ 540,927
Ending Balance, Issued Shares at Mar. 31, 2018		31,458,976
Ending Balance, Value at Mar. 31, 2018		$ 3,146	0	523,668	42,895	(28,782)
Beginning Balance, Issued Shares at Dec. 31, 2018	30,567,725	30,567,725
Beginning Balance, Value at Dec. 31, 2018	$ 478,195	$ 3,057	3,397	535,118	66,242	(63,377)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2018	544,437
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	25,710			25,710
Net Income (Loss) Attributable to Noncontrolling Interest	(667)				(667)
Cumulative translation adjustment	3,482					3,482
Repurchase and retirement of common stock, Shares		(50,000)
Repurchase and retirement of common stock, Value	(2,172)	$ (5)	0	(2,167)
Vesting of restricted stock, Shares		6,382
Vesting of restricted stock, Value	0	$ 0	0
Share based compensation	576		576
Forfeiture of certain shares to satisfy exercise costs and the recipients income tax obligations related to stock options exercised and restricted stock vested, Shares		(351)
Forfeiture of certain shares to satisfy exercise costs and the recipients income tax obligations related to stock options exercised and restricted stock vested	(21)	$ 0	(21)
Recognized controlling ownership of joint venture	0		398		(398)
Dividends paid	(2,297)			(2,297)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Mar. 31, 2019	$ 569,048
Ending Balance, Issued Shares at Mar. 31, 2019	30,523,756	30,523,756
Ending Balance, Value at Mar. 31, 2019	$ 503,871	$ 3,052	$ 4,350	$ 556,364	$ 65,177	$ (59,895)