Shareholders' Equity and Noncontrolling Interests (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period	$ 4,043.4	$ 3,723.1
Net income	268.3	227.3
Other comprehensive income	62.8	67.2
Acquisition resulting in noncontrolling interest	0.1
Distributions to shareholders of noncontrolling interests	(3.9)	(4.2)
Purchase of treasury stock	(382.0)	(249.2)
Stock options exercised	20.7	23.7
Dividends declared	(57.4)	(48.9)
Stock-based compensation expense	12.7	12.1
Balance at end of period	$ 3,967.9	$ 3,751.1
Common Stock
Increase (Decrease) In Shareholders' Equity
Balance (in shares)	305.7	308.3
Balance at beginning of period	$ 0.3	$ 0.3
Retirement of treasury stock (in shares)	(4.2)	(3.7)
Stock options exercised (in shares)	0.6	0.8
Balance (in shares)	302.1	305.4
Balance at end of period	$ 0.3	$ 0.3
Additional Paid-In Capital
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period	1,249.0	1,020.9
Stock options exercised	20.7	23.7
Stock-based compensation expense	12.7	12.1
Balance at end of period	1,282.4	1,056.7
Retained Earnings
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period	2,941.5	3,122.7
Net income	265.6	224.9
Retirement of treasury stock	(382.0)	(249.2)
Dividends declared	(57.4)	(48.9)
Balance at end of period	2,770.9	3,049.5
Accumulated Other Comprehensive Loss
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period	(201.0)	(469.0)
Other comprehensive income	61.3	66.7
Balance at end of period	(139.7)	(402.3)
Treasury Stock
Increase (Decrease) In Shareholders' Equity
Purchase of treasury stock	(382.0)	(249.2)
Retirement of treasury stock	382.0	249.2
Noncontrolling Interests
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period	53.6	48.2
Net income	2.7	2.4
Other comprehensive income	1.5	0.5
Acquisition resulting in noncontrolling interest	0.1
Distributions to shareholders of noncontrolling interests	(3.9)	(4.2)
Balance at end of period	54.0	$ 46.9
Impact of ASU 2014-09
Increase (Decrease) In Shareholders' Equity
Cumulative effect of adoption of revenue recognition standard (Note 2)	3.2
Impact of ASU 2014-09 | Retained Earnings
Increase (Decrease) In Shareholders' Equity
Cumulative effect of adoption of revenue recognition standard (Note 2)	$ 3.2