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, 2015	$ 4,860,863	$ 21,952	$ 813	$ 1,760,016	$ 4,102,707	$ (793,568)	$ (215,795)	$ 6,690
Beginning 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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under employee and director stock plans	(8,377)		$ 2	(8,400)			$ 21
Shares issued under employee and director stock plans (in shares)			191,000				1,000
Stock-based compensation expense	31,382			31,382
Repurchases of common stock (in shares)			(2,306,000)
Repurchases of common stock	(274,144)		$ (23)		(274,121)
Accretion of redeemable noncontrolling interest	(3,892)	3,892			(3,892)
Noncontrolling earnings	677	2,474						677
Currency translation adjustment on noncontrolling interests	(1,219)	(1,945)						(1,219)
Purchase of redeemable noncontrolling interest and noncontrolling interest, net of taxes	0	(33,884)		1,060				(1,060)
Currency translation adjustment	(234,175)					(234,175)
Prior pension and post-retirement benefit service cost and actuarial gain (loss)	1,094					1,094
Net income	861,704				861,704
Ending balance at Dec. 31, 2018	$ 7,440,059	$ 0	$ 797	$ 1,852,173	$ 6,588,197	$ (791,608)	$ (215,745)	$ 6,245
Ending balance (in shares) at Dec. 31, 2018			79,656,000				(7,349,000)