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	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)	19,931			16,971		2,960
Issuance of shares pursuant to restricted/performance stock units (in shares)								64,111		49,672
Issuance of shares pursuant to restricted/performance stock units							$ 1	$ 1
Issuance of shares pursuant to deferred stock unit awards (in shares)		17,028
Forfeitures of restricted shares (in shares)		(1,084)
Shares repurchased and retired (in shares)		(965,537)
Shares repurchased and retired	(21,034)	$ (10)	(21,024)
Equity-based compensation expense	6,736		6,736
Distributions to non-controlling interests	35					35
Currency translation adjustment and derivative transactions, net	16,598				16,578	20
Balance (in shares) at Jun. 30, 2017		33,120,494
Balance at Jun. 30, 2017	598,380	$ 331	152,310	472,033	(36,922)	10,628
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustmen	$ 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)	5,722			5,852		(130)
Issuance of shares pursuant to restricted/performance stock units (in shares)								295,420		296,909
Issuance of shares pursuant to restricted/performance stock units							$ 3	$ 3	$ 3	$ 3
Issuance of shares pursuant to deferred stock unit awards (in shares)		20,939
Shares repurchased and retired (in shares)		(772,172)
Shares repurchased and retired	(18,609)	$ (8)	(18,601)
Equity-based compensation expense	5,094		5,094
Currency translation adjustment and derivative transactions, net	$ (3,099)				(2,852)	(247)
Balance (in shares) at Jun. 30, 2018	32,303,638	32,303,638
Balance at Jun. 30, 2018	$ 494,438	$ 323	$ 127,242	$ 392,128	$ (35,688)	$ 10,433