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	$ 167,700	$ 446,095	$ (45,635)	$ 7,683
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(54,198)			(56,612)		2,414
Issuance of shares pursuant to restricted/performance stock units (in shares)								90,663		49,672
Issuance of shares pursuant to restricted/performance stock units							$ 1	$ 1
Issuance of shares pursuant to deferred stock unit awards (in shares)		30,559
Forfeitures of restricted shares (in shares)		(1,084)
Shares repurchased and retired (in shares)		(1,452,296)
Shares repurchased and retired	(31,730)	$ (14)	(31,716)
Equity-based compensation expense	8,104		8,104
Investments from non-controlling interests	158					158
Distributions/Sale of to non-controlling interests	(71)					(71)
Currency translation adjustments, derivative transactions and pension activity, net	17,877				17,791	86
Balance (in shares) at Sep. 30, 2017		32,673,818
Balance at Sep. 30, 2017	516,324	$ 327	144,088	389,483	(27,844)	10,270
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment	$ 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	376,694	(23,522)	10,810
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	5,863			5,405		458
Issuance of shares pursuant to restricted/performance stock units (in shares)								301,041		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)		26,396
Shares repurchased and retired (in shares)		(772,898)
Shares repurchased and retired	(18,628)	$ (8)	(18,620)
Equity-based compensation expense	6,201		6,201
Distributions/Sale of to non-controlling interests	(3,361)					(3,361)
Currency translation adjustments, derivative transactions and pension activity, net	$ (9,321)				(9,146)	(175)
Balance (in shares) at Sep. 30, 2018	32,313,990	32,313,990
Balance at Sep. 30, 2018	$ 486,084	$ 323	$ 128,330	$ 382,367	$ (32,668)	$ 7,732