Consolidated Statement of Stockholders' Equity (USD $) In Thousands, except Share data	Total	Stockholders' Equity of the Company Preferred Stock [Member]	Stockholders' Equity of the Company Common Stock [Member]	Stockholders' Equity of the Company Treasury Stock [Member]	Stockholders' Equity of the Company Additional Paid-in Capital [Member]	Stockholders' Equity of the Company Accumulated Other Comprehensive Income (Loss) [Member]	Stockholders' Equity of the Company Retained Earnings [Member]	Noncontrolling Interest [Member]
Beginning balance,value at Dec. 31, 2011	$ 470,247	$ 0	$ 566	$ (357,267)	$ 350,386	$ (5,474)	$ 470,776	$ 11,260
Preferred stock beginning balance, share at Dec. 31, 2011		0	56,635
Net income	73,923						70,015
Net income excluding mandatorily redeemable noncontrolling interest	73,923							3,908
Acquisition of noncontrolling interest	941							941
Dividends distributed to noncontrolling interest	(2,205)							(2,205)
Transfer of noncontrolling interest to mandatorily redeemable noncontrolling interest	(1,067)							(1,067)
Foreign currency translation adjustments	12,648					12,517		131
Derivatives valuation, net of tax	15,411					15,411
Vesting of restricted stock units, share			575
Vesting of restricted stock units, value	(4,580)		5	8,041	(12,626)
Exercise of stock options, share			121
Exercise of stock options, value	1,374		1	1,703	(330)
Excess tax benefit from equity-based awards	(1)				(1)
Equity-based compensation expense	13,295				13,285			10
Purchases of common stock, share			(5,043)
Purchases of common stock, value	(81,243)		(50)	(81,193)
Other, net of tax	527					527
Ending balance,value at Dec. 31, 2012	499,270	0	522	(428,716)	350,714	22,981	540,791	12,978
Preferred stock ending balance, share at Dec. 31, 2012		0
Common stock ending balance, share at Dec. 31, 2012			52,288
Net income	71,471						67,388
Net income excluding mandatorily redeemable noncontrolling interest	70,989							3,601
Dividends distributed to noncontrolling interest	(4,183)							(4,183)
Purchases of outstanding noncontrolling interest	(425)				3,715			(4,140)
Adjustments to redemption value of mandatorily redeemable noncontrolling interest	(1,677)						(1,677)
Deconsolidation of a subsidiary	(121)							(121)
Foreign currency translation adjustments	(26,342)					(26,254)		(88)
Derivatives valuation, net of tax	(17,911)					(17,911)
Vesting of restricted stock units, share			455
Vesting of restricted stock units, value	(4,974)		5	6,530	(11,509)
Exercise of stock options, share			91
Exercise of stock options, value	862		1	1,294	(433)
Excess tax benefit from equity-based awards	787				787
Equity-based compensation expense	13,141				13,107			34
Purchases of common stock, share			(2,481)
Purchases of common stock, value	(56,532)		(25)	(56,507)
Other, net of tax	598					598
Ending balance,value at Dec. 31, 2013	473,482	0	503	(477,399)	356,381	(20,586)	606,502	8,081
Preferred stock ending balance, share at Dec. 31, 2013	0	0
Common stock ending balance, share at Dec. 31, 2013	50,352,881		50,353
Net income	77,417						72,293
Net income excluding mandatorily redeemable noncontrolling interest	76,805							4,512
Dividends distributed to noncontrolling interest	(4,275)							(4,275)
Adjustments to redemption value of mandatorily redeemable noncontrolling interest	(936)						(936)
Foreign currency translation adjustments	(23,120)					(22,771)		(349)
Derivatives valuation, net of tax	(9,993)					(9,993)
Vesting of restricted stock units, share			396
Vesting of restricted stock units, value	(5,379)		4	5,979	(11,362)
Exercise of stock options, share	(53,100)		58
Exercise of stock options, value	443		1	876	(434)
Excess tax benefit from equity-based awards	1,015				1,015
Equity-based compensation expense	11,206				11,192			14
Purchases of common stock, share			(2,354)
Purchases of common stock, value	(57,074)		(23)	(57,051)
Other, net of tax	1,076					1,076
Ending balance,value at Dec. 31, 2014	$ 463,250	$ 0	$ 485	$ (527,595)	$ 356,792	$ (52,274)	$ 677,859	$ 7,983
Preferred stock ending balance, share at Dec. 31, 2014	0	0
Common stock ending balance, share at Dec. 31, 2014	48,452,852		48,453