Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Redeemable Noncontrolling Interest	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Noncontrolling Interest
Beginning balance at Dec. 31, 2014	$ 4,422,813	$ 0	$ 811	$ 1,598,887	$ 3,487,079	$ (429,321)	$ (239,450)	$ 4,807
Beginning balance (in shares) at Dec. 31, 2014			81,070,000				(8,157,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
IVC Group acquisition	153,096			129,445			$ 23,651
IVC Group acquisition (in shares)							806,000
Shares issued under employee and director stock plans	(6,530)		$ 2	(6,536)			$ 4
Shares issued under employee and director stock plans (in shares)			210,000
Stock-based compensation expense	32,552			32,552
Tax benefit from stock-based compensation	5,668			5,668
Accretion of redeemable noncontrolling interest	(194)	194			(194)
Noncontrolling earnings	256	1,428						256
Currency translation adjustment on noncontrolling interests	(970)	(713)						(970)
Acquisition of noncontrolling interest, net of taxes	3,117	21,043			520			2,597
Currency translation adjustment	(360,147)					(360,147)
Prior pension and post-retirement benefit service cost and actuarial gain (loss)	(4,100)					(4,100)
Net income	615,302				615,302
Ending balance at Dec. 31, 2015	4,860,863	21,952	$ 813	1,760,016	4,102,707	(793,568)	$ (215,795)	6,690
Ending balance (in shares) at Dec. 31, 2015			81,280,000				(7,351,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under employee and director stock plans	(8,226)		$ 2	(8,232)			$ 4
Shares issued under employee and director stock plans (in shares)			239,000
Stock-based compensation expense	35,059			35,059
Tax benefit from stock-based compensation	4,697			4,697
Accretion of redeemable noncontrolling interest	(123)	123			(123)
Noncontrolling earnings	340	2,864						340
Currency translation adjustment on noncontrolling interests	(26)	(1,243)						(26)
Acquisition of noncontrolling interest, net of taxes	0				(32)			32
Currency translation adjustment	(36,702)					(36,702)
Prior pension and post-retirement benefit service cost and actuarial gain (loss)	(2,757)					(2,757)
Net income	930,362				930,362
Ending balance at Dec. 31, 2016	5,783,487	23,696	$ 815	1,791,540	5,032,914	(833,027)	$ (215,791)	7,036
Ending balance (in shares) at Dec. 31, 2016			81,519,000				(7,351,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under employee and director stock plans	297		$ 3	269			$ 25
Shares issued under employee and director stock plans (in shares)			252,000				1,000
Stock-based compensation expense	36,322			36,322
Distribution to noncontrolling interest, net of adjustments	(750)							(750)
Accretion of redeemable noncontrolling interest	(46)	46			(46)
Noncontrolling earnings	510	2,544						510
Currency translation adjustment on noncontrolling interests	1,051	3,177						1,051
Currency translation adjustment	277,427					277,427
Prior pension and post-retirement benefit service cost and actuarial gain (loss)	(2,927)					(2,927)
Net income	971,638				971,638
Ending balance at Dec. 31, 2017	$ 7,067,009	$ 29,463	$ 818	$ 1,828,131	$ 6,004,506	$ (558,527)	$ (215,766)	$ 7,847
Ending balance (in shares) at Dec. 31, 2017			81,771,000				(7,350,000)