CONSOLIDATED STATEMENTS OF STOCKHOLDERS' INVESTMENT - USD ($) shares in Thousands, $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance		$ 1,047,015		$ 939,724	$ 1,047,015	$ 939,724	$ 1,504,372
Net income	$ 126,583	$ 106,476	$ 112,947	$ 93,187	509,699	449,711	415,904
Foreign currency translation adjustment					(9,336)	(17,990)	(1,275)
Dividends declared, $1.57 in 2015, $1.43 in 2014 and $1.40 in 2013 per share					(235,618)	(215,005)	(220,300)
Stock issued for employee benefit plans					4,188	(667)	(34,978)
Stock-based compensation expense					58,067	47,721	9,096
Excess tax benefit on deferred compensation and employee stock plans					8,548	7,558	27,209
Repurchase of common stock					(232,113)	(164,037)	(760,304)
Ending Balance	$ 1,150,450		$ 1,047,015		$ 1,150,450	$ 1,047,015	$ 939,724
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance (in shares)		146,458		150,197	146,458	150,197	161,327
Beginning Balance		$ 14,646		$ 15,020	$ 14,646	$ 15,020	$ 16,133
Stock issued for employee benefit plans (in shares)					254	405	263
Stock issued for employee benefit plans					$ 25	$ 40	$ 26
Issuance of restricted stock (in shares)					164	(410)	335
Issuance of restricted stock					$ 16	$ (41)	$ 34
Stock-based compensation expense (in shares)						30	30
Stock-based compensation expense						$ 3	$ 3
Repurchase of common stock (in shares)					(3,421)	(3,764)	(11,758)
Repurchase of common stock					$ (342)	$ (376)	$ (1,176)
Ending Balance (in shares)	143,455		146,458		143,455	146,458	150,197
Ending Balance	$ 14,345		$ 14,646		$ 14,345	$ 14,646	$ 15,020
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance		321,968		217,894	321,968	217,894	303,479
Stock issued for employee benefit plans					(9,095)	(24,644)	(45,106)
Issuance of restricted stock					(16)	41	(34)
Stock-based compensation expense					58,039	46,119	7,346
Excess tax benefit on deferred compensation and employee stock plans					8,548	7,558	27,209
Repurchase of common stock						75,000	(75,000)
Ending Balance	379,444		321,968		379,444	321,968	217,894
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance		2,648,539		2,413,833	2,648,539	2,413,833	2,218,229
Net income					509,699	449,711	415,904
Dividends declared, $1.57 in 2015, $1.43 in 2014 and $1.40 in 2013 per share					(235,618)	(215,005)	(220,300)
Ending Balance	2,922,620		2,648,539		2,922,620	2,648,539	2,413,833
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance		(28,610)		(10,620)	(28,610)	(10,620)	(9,345)
Foreign currency translation adjustment					(9,336)	(17,990)	(1,275)
Ending Balance	(37,946)		(28,610)		(37,946)	(28,610)	(10,620)
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance		$ (1,909,528)		$ (1,696,403)	(1,909,528)	(1,696,403)	(1,024,124)
Stock issued for employee benefit plans					13,258	23,937	10,102
Stock-based compensation expense					28	1,599	1,747
Repurchase of common stock					(231,771)	(238,661)	(684,128)
Ending Balance	$ (2,128,013)		$ (1,909,528)		$ (2,128,013)	$ (1,909,528)	$ (1,696,403)