Condensed Consolidated Statements of Stockholders' Investment - USD ($) shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 1,587,118	$ 1,670,730	$ 1,652,561	$ 1,595,087	$ 1,670,730	$ 1,595,087
Net income	143,939	78,146	169,180	161,788	222,085	330,968
Foreign currency adjustments, net of tax	24,253	(32,195)	(5,688)	5,297
Dividends declared	(69,791)	(69,871)	(69,268)	(69,683)
Stock issued for employee benefit plans	7,855	(2,526)	7,699	7,573
Issuance of restricted stock, net of forfeitures		0	0	0
Stock-based compensation expense	10,954	11,397	14,684	17,123
Repurchase of common stock		(68,563)	(109,857)	(64,624)
Ending balance	$ 1,704,328	$ 1,587,118	$ 1,659,311	$ 1,652,561	$ 1,704,328	$ 1,659,311
Dividends declared, per share (in dollars per share)	$ 0.51	$ 0.51	$ 0.50	$ 0.50
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)	134,586	134,895	136,889	137,284	134,895	137,284
Beginning balance	$ 13,459	$ 13,490	$ 13,689	$ 13,728	$ 13,490	$ 13,728
Stock issued for employee benefit plans (in shares)	138	343	129	342
Stock issued for employee benefit plans	$ 13	$ 34	$ 13	$ 34
Issuance of restricted stock, net of forfeitures (in shares)		321	23
Issuance of restricted stock, net of forfeitures (in shares)				(3)
Issuance of restricted stock, net of forfeitures		$ 32	$ 2	$ 0
Stock-based compensation expense (in shares)	0	0	0	0
Stock-based compensation expense	$ 0	$ 0	$ 0	$ 0
Repurchase of common stock (in shares)		(973)	(1,310)	(734)
Repurchase of common stock		$ (97)	$ (131)	$ (73)
Ending balance (in shares)	134,724	134,586	135,731	136,889	134,724	135,731
Ending balance	$ 13,472	$ 13,459	$ 13,573	$ 13,689	$ 13,472	$ 13,573
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	533,819	546,646	527,089	521,486	546,646	521,486
Stock issued for employee benefit plans	(1,165)	(24,192)	(681)	(11,520)
Issuance of restricted stock, net of forfeitures		(32)	(2)	0
Stock-based compensation expense	10,954	11,397	14,684	17,123
Ending balance	543,608	533,819	541,090	527,089	543,608	541,090
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	4,153,109	4,144,834	3,937,698	3,845,593	4,144,834	3,845,593
Net income	143,939	78,146	169,180	161,788
Dividends declared	(69,791)	(69,871)	(69,268)	(69,683)
Ending balance	4,227,257	4,153,109	4,037,610	3,937,698	4,227,257	4,037,610
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(108,344)	(76,149)	(66,638)	(71,935)	(76,149)	(71,935)
Foreign currency adjustments, net of tax	24,253	(32,195)	(5,688)	5,297
Ending balance	(84,091)	(108,344)	(72,326)	(66,638)	(84,091)	(72,326)
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(3,004,925)	(2,958,091)	(2,759,277)	(2,713,785)	(2,958,091)	(2,713,785)
Stock issued for employee benefit plans	9,007	21,632	8,367	19,059
Stock-based compensation expense	0	0	0	0
Repurchase of common stock		(68,466)	(109,726)	(64,551)
Ending balance	$ (2,995,918)	$ (3,004,925)	$ (2,860,636)	$ (2,759,277)	$ (2,995,918)	$ (2,860,636)