Consolidated Statements of Equity (Unaudited) (USD $) In Thousands, except Share data	Restricted Stock [Member] Common Stock [Member] USD ($)	Restricted Stock [Member] USD ($)	Restricted Stock Units (RSUs) [Member] Common Stock [Member]	Common Stock [Member] USD ($)	Additional Paid-in Capital [Member] USD ($)	Retained Earnings [Member] USD ($)	Accumulated Other Comprehensive Income (Loss) [Member] USD ($)	Noncontrolling Interest [Member] USD ($)	Total USD ($)
Balance at Dec. 31, 2011				$ 394	$ 260,680	$ 373,796	$ 5,862	$ 8,257	$ 648,989
Balance (in Shares) at Dec. 31, 2011				39,352,375
Net income						18,222		865	19,087
Issuance of common stock upon stock option exercises including tax benefit				1	619				620
Issuance of common stock upon stock option exercises including tax benefit (in Shares)				25,123
Restricted shares issued	3	3
Restricted shares issued (in Shares)	266,715		11,936
Issuance of shares pursuant to deferred stock unit awards (in Shares)				22,185
Forfeitures of restricted shares (in Shares)				(18,861)
Shares repurchased and retired				(5)	(6,259)				(6,264)
Shares repurchased and retired (in Shares)				(379,674)
Equity-based compensation expense					4,010				4,010
Investment by non-controlling interests								4,939	4,939
Currency translation adjustment and derivative transactions, net							(407)	(5)	(412)
Balance at Jun. 30, 2012				393	259,050	392,018	5,455	14,056	670,972
Balance (in Shares) at Jun. 30, 2012				39,279,799
Balance at Dec. 31, 2012				390	257,209	426,457	15,260	16,804	716,120
Balance (in Shares) at Dec. 31, 2012				38,952,561					38,952,561
Net income						15,924		832	16,756
Issuance of common stock upon stock option exercises including tax benefit				0	897				897
Issuance of common stock upon stock option exercises including tax benefit (in Shares)				29,511
Restricted shares issued	4	4
Restricted shares issued (in Shares)	398,497		11,112
Issuance of shares pursuant to deferred stock unit awards (in Shares)				3,171
Forfeitures of restricted shares (in Shares)				(13,992)
Shares repurchased and retired				(7)	(15,815)				(15,822)
Shares repurchased and retired (in Shares)				(696,310)
Equity-based compensation expense					3,973				3,973
Currency translation adjustment and derivative transactions, net							(9,913)	(282)	(10,195)
Balance at Jun. 30, 2013				$ 387	$ 246,264	$ 442,381	$ 5,347	$ 17,354	$ 711,733
Balance (in Shares) at Jun. 30, 2013				38,684,550					38,684,550