Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member]	Restricted Shares [Member]	Restricted Shares [Member] Common Stock [Member]	Restricted Stock Units [Member] Common Stock [Member]
Balance at Dec. 31, 2013	$ 726,921	$ 380	$ 236,128	$ 470,808	$ 2,052	$ 17,553
Balance (in Shares) at Dec. 31, 2013		37,983,114
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	16,840			16,783		57
Issuance of common stock upon stock option exercises	5,031	$ 3	5,028
Issuance of common stock upon stock option exercises (in Shares)		322,173
Restricted shares issued							$ 2	$ 2
Restricted shares issued (in Shares)								222,944	15,277
Issuance of shares pursuant to deferred stock unit awards (in Shares)		30,594
Forfeitures of restricted shares	(1)	$ (1)
Forfeitures of restricted shares (in Shares)		(59,632)
Shares repurchased and retired	(20,661)	$ (8)	(20,653)
Shares repurchased and retired (in Shares)		(882,840)
Equity-based compensation expense	3,120		3,120
Purchase of non-controlling interest	(617)		(909)			292
Currency translation adjustment and derivative transactions, net	(587)				(553)	(34)
Balance at Jun. 30, 2014	730,048	$ 376	222,714	487,591	1,499	17,868
Balance (in Shares) at Jun. 30, 2014		37,631,630
Balance at Dec. 31, 2014	$ 645,085	$ 374	217,289	433,641	(24,669)	18,450
Balance (in Shares) at Dec. 31, 2014	37,360,515	37,360,515
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 10,220			10,043		177
Issuance of common stock upon stock option exercises	$ 1,121	$ 1	1,120
Issuance of common stock upon stock option exercises (in Shares)	100,191	100,191
Restricted shares issued (in Shares)									10,856
Issuance of shares pursuant to deferred stock unit awards (in Shares)		12,819
Forfeitures of restricted shares (in Shares)		(45,207)
Shares repurchased and retired	$ (21,926)	$ (13)	(21,913)
Shares repurchased and retired (in Shares)		(1,211,333)
Equity-based compensation expense	4,582		4,582
Currency translation adjustment and derivative transactions, net	(18,095)				(16,781)	(1,314)
Balance at Jun. 30, 2015	$ 620,987	$ 362	$ 201,078	$ 443,684	$ (41,450)	$ 17,313
Balance (in Shares) at Jun. 30, 2015	36,227,841	36,227,841