Consolidated Statement of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss), Net of Tax	Noncontrolling Interests In Consolidated Subsidiary
Balance (in shares) at Dec. 31, 2015		346.0			0.4
Balance at Dec. 31, 2015	$ 7,776.6	$ 3.5	$ 4,677.7	$ 3,138.3	$ (14.9)	$ (30.5)	$ 2.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	613.2			612.6			0.6
Change in the value of derivative instruments, net of tax	38.3					38.3
Employee benefit plan liability adjustments, net of tax	6.4					6.4
Cash dividends declared	(423.8)			(423.8)
Issuances of common stock (in shares)		2.2			0.0
Issuances of common stock	60.5		60.5		$ 0.0
Stock-based compensation	23.2		26.3	(3.1)
Purchase of common stock for treasury (in shares)					(8.4)
Purchase of common stock for treasury	(400.0)				$ (400.0)
Distributions paid	(0.7)						(0.7)
Balance (in shares) at Dec. 31, 2016		348.2			8.8
Balance at Dec. 31, 2016	7,693.7	$ 3.5	4,764.5	3,324.0	$ (414.9)	14.2	2.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,279.0			1,278.4			0.6
Change in the value of derivative instruments, net of tax	4.7					4.7
Employee benefit plan liability adjustments, net of tax	3.7					3.7
Cash dividends declared	(446.3)			(446.3)
Issuances of common stock (in shares)		1.9			0.0
Issuances of common stock	36.9		36.9		$ 0.0
Stock-based compensation	34.6		38.2	(3.6)
Purchase of common stock for treasury (in shares)					(9.6)
Purchase of common stock for treasury	(644.5)				$ (644.5)
Distributions paid	(0.7)						(0.7)
Balance (in shares) at Dec. 31, 2017		350.1			18.4
Balance at Dec. 31, 2017	7,961.1	$ 3.5	4,839.6	4,152.5	$ (1,059.4)	22.6	2.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of accounting standard, net of tax | Accounting Standards Update 2014-09	33.4			33.4
Net income	1,037.6			1,036.9			0.7
Change in the value of derivative instruments, net of tax	14.7					14.7
Employee benefit plan liability adjustments, net of tax	(6.5)					(6.5)
Cash dividends declared	(468.4)			(468.4)
Issuances of common stock (in shares)		1.8			(0.3)
Issuances of common stock	23.2		43.3		$ (20.1)
Stock-based compensation	38.1		42.0	(3.9)
Purchase of common stock for treasury (in shares)					(10.7)
Purchase of common stock for treasury	(703.1)				$ (703.1)
Distributions paid	(0.6)						(0.6)
Balance (in shares) at Dec. 31, 2018		351.9			29.4
Balance at Dec. 31, 2018	$ 7,929.5	$ 3.5	$ 4,924.9	$ 4,750.5	$ (1,782.6)	$ 30.8	$ 2.4