CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest
Beginning Balance at Dec. 31, 2012	$ 1,557,323	$ 860	$ 116,720	$ 1,463,277	$ (39,064)	$ 15,530
Beginning Balance (in shares) at Dec. 31, 2012		85,988,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	313,084			311,372		1,712
Currency translation adjustment	(19,160)				(17,718)	(1,442)
Change in qualifying cash flow hedge, net of tax	314				314
Issuance of common stock for exercise of options, restricted stock units and employee stock purchases (in shares)		973,000
Issuance of common stock for exercise of options, restricted stock units and employee stock purchases	48,001	10	47,991
Purchase/ cancellation of treasury stock (in shares)		(1,461,000)
Purchase/ cancellation of treasury stock	(163,700)	(15)	0	(163,685)
Stock compensation expense	17,457		17,457
Excess tax benefit of stock options exercised	17,153		17,153
Noncontrolling interests attributable to acquisitions	4,211					4,211
Reduction to noncontrolling interests due to additional ownership	(7,137)		(4,211)			(2,926)
Payments to noncontrolling interests	(8)					(8)
Ending Balance at Dec. 31, 2013	1,767,538	855	195,110	1,610,964	(56,468)	17,077
Ending Balance (in shares) at Dec. 31, 2013	85,500,037	85,500,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	245,488			243,930		1,558
Currency translation adjustment	(40,777)				(38,829)	(1,948)
Change in qualifying cash flow hedge, net of tax	(54)				(54)
Issuance of common stock for exercise of options, restricted stock units and employee stock purchases (in shares)		686,000
Issuance of common stock for exercise of options, restricted stock units and employee stock purchases	37,426	7	37,419
Purchase/ cancellation of treasury stock (in shares)	(1,411,961)	(1,412,000)
Purchase/ cancellation of treasury stock	(160,359)	(14)	0	(160,345)
Stock compensation expense	13,365		13,365
Excess tax benefit of stock options exercised	10,747		10,747
Noncontrolling interests attributable to acquisitions	6,943					6,943
Reduction to noncontrolling interests due to additional ownership	(130)					(130)
Ending Balance at Sep. 30, 2014	$ 1,880,187	$ 848	$ 256,641	$ 1,694,549	$ (95,351)	$ 23,500
Ending Balance (in shares) at Sep. 30, 2014	84,774,015	84,774,000