Consolidated Statements of Stockholders' Equity (USD $) In Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
Beginning Balances at Dec. 31, 2010	$ 1,009,485	$ 86	$ 347,848	$ 650,253	$ 737	$ 10,561
Beginning Balances, shares at Dec. 31, 2010		86,179
Net income (excludes $1,555 and $450 in 2011, $962 and $1,555 in 2012 and $1,233 and $2,003 in 2013 related to redeemable and mandatorily redeemable noncontrolling interests, respectively)	97,855	0	0	95,405	0	2,450
Net Income (Loss) Attributable to Parent	95,405
Foreign currency translation adjustment	(319)
Distribution to noncontrolling interests	(1,952)	0	0	0	0	(1,952)
Purchase of noncontrolling interests	(722)	0	(263)	0	0	(985)
Share-based compensation	10,773	0	10,773	0	0	0
Stock Issued During Period, Value, Acquisitions	0
Shares Paid for Tax Withholding for Share Based Compensation		(114)
Issuance of common stock under stock incentive plans	3,999	1	3,998	0	0	0
Issuance of common stock under stock incentive plans, shares		731
Stock repurchases	(2,673)	0	(2,673)	0	0	0
Excess tax benefit from stock options	1,708	0	1,708	0	0	0
Tax shortfall and other from stock options and awards	202	0	202	0	0	0
Other Comprehensive Income (Loss), Net of Tax	(319)	0	0	0	(319)	0
Noncontrolling Interest, Increase from Business Combination	0
Ending Balances at Dec. 31, 2011	1,117,952	87	361,715	745,658	418	10,074
Ending Balances, shares at Dec. 31, 2011		86,796
Net income (excludes $1,555 and $450 in 2011, $962 and $1,555 in 2012 and $1,233 and $2,003 in 2013 related to redeemable and mandatorily redeemable noncontrolling interests, respectively)	48,199	0	0	45,551	0	2,648
Net Income (Loss) Attributable to Parent	45,551
Foreign currency translation adjustment	1,429
Distribution to noncontrolling interests	(1,832)	0	0	0	0	(1,832)
Share-based compensation	14,087	0	14,087	0	0	0
Stock Issued During Period, Value, Acquisitions	10,500	0	10,500	0	0	0
Shares Paid for Tax Withholding for Share Based Compensation		(403)
Issuance of common stock under stock incentive plans	9,533	1	9,532	0	0	0
Stock Issued During Period, Shares, Acquisitions	473
Issuance of common stock under stock incentive plans, shares		1,506
Stock repurchases	(8,216)	0	(8,216)	0	0	0
Excess tax benefit from stock options	2,868	0	2,868	0	0	0
Tax shortfall and other from stock options and awards	127	0	127	0	0	0
Other Comprehensive Income (Loss), Net of Tax	1,429	0	0	0	1,429	0
Noncontrolling Interest, Increase from Business Combination	(8,161)
Ending Balances at Dec. 31, 2012	1,194,393	88	390,359	791,209	1,847	10,890
Ending Balances, shares at Dec. 31, 2012		88,372
Net income (excludes $1,555 and $450 in 2011, $962 and $1,555 in 2012 and $1,233 and $2,003 in 2013 related to redeemable and mandatorily redeemable noncontrolling interests, respectively)	139,686	0	0		0	2,175
Net Income (Loss) Attributable to Parent	137,511
Foreign currency translation adjustment	(7,999)
Distribution to noncontrolling interests	(1,886)	0	0	0	0	(1,886)
Purchase of noncontrolling interests	(5,094)	0	(785)	0	0	(4,309)
Share-based compensation	14,104	0	14,104	0	0	0
Stock Issued During Period, Value, Acquisitions	0
Stock Repurchased and Retired During Period, Shares		(1,423)
Stock Repurchased and Retired During Period, Value	(39,367)	(1)	(39,366)	0	0	0
Issuance of common stock under stock incentive plans	17,233	2	17,231	0	0	0
Issuance of common stock under stock incentive plans, shares		1,559
Excess tax benefit from stock options	3,446	0	3,446	0	0	0
Tax shortfall and other from stock options and awards	268	0	268	0	0	0
Other Comprehensive Income (Loss), Net of Tax	(7,999)	0	0	0	(8,037)	(6)
Other Comprehensive Income Net Of Tax, excluding mandatorily redeemable partnership interests	(8,043)
Noncontrolling Interest, Increase from Business Combination	3,336	0	0	0	0	3,336
Ending Balances at Dec. 31, 2013	$ 1,317,540	$ 89	$ 384,721	$ 928,720	$ (6,190)	$ 10,200
Ending Balances, shares at Dec. 31, 2013		88,508