Consolidated Statements of Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Non- Controlling Interests	Restricted Stock Units	Restricted Stock Units Common Stock	Performance Units Common Stock
Balance (in shares) at Dec. 31, 2016		33,956,304
Balance at Dec. 31, 2016	$ 576,183	$ 340	$ 166,598	$ 455,062	$ (53,500)	$ 7,683
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	7,753			5,871		1,882
Issuance of shares pursuant to restricted stock units (in shares)								62,279	49,672
Issuance of shares pursuant to restricted stock units							$ 1	$ 1
Forfeitures of restricted shares (in shares)		(1,084)
Shares repurchased and retired (in shares)		(462,317)
Shares repurchased and retired	(10,508)	$ (5)	(10,503)
Equity-based compensation expense	3,096		3,096
Currency translation adjustment and derivative transactions, net	4,347				4,360	(13)
Balance (in shares) at Mar. 31, 2017		33,604,854
Balance at Mar. 31, 2017	580,872	$ 336	159,191	460,933	(49,140)	9,552
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment (see Revenues: Note 3)	$ 268			268
Balance (in shares) at Dec. 31, 2017	32,462,542	32,462,542
Balance at Dec. 31, 2017	$ 505,056	$ 325	140,749	386,008	(32,836)	10,810
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(1,476)			(2,069)		593
Issuance of shares pursuant to restricted stock units (in shares)								275,384	296,909
Issuance of shares pursuant to restricted stock units	3							$ 3	$ 3
Issuance of shares pursuant to deferred stock unit awards (in shares)		4,568
Shares repurchased and retired (in shares)		(571,580)
Shares repurchased and retired	(13,676)	$ (6)	(13,670)
Equity-based compensation expense	2,158		2,158
Currency translation adjustment and derivative transactions, net	$ 2,715				2,662	53
Balance (in shares) at Mar. 31, 2018	32,467,823	32,467,823
Balance at Mar. 31, 2018	$ 495,051	$ 325	$ 129,237	$ 384,207	$ (30,174)	$ 11,456