Shareholders' Equity and Noncontrolling Interests (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period	$ 4,064.2	$ 4,043.4
Net income	269.9	268.3
Other comprehensive (loss) income	6.3	62.8
Acquisition resulting in noncontrolling interest		0.1
Distributions to shareholders of noncontrolling interests	(3.2)	(3.9)
Purchase of treasury stock	(160.0)	(382.0)
Stock options exercised	47.3	20.7
Dividends declared	$ (68.5)	$ (57.4)
Dividends declared per share (in dollars per share)	$ 0.23	$ 0.19
Stock-based compensation expense	$ 14.4	$ 12.7
Balance at end of period	$ 4,170.4	$ 3,967.9
Common Stock
Increase (Decrease) In Shareholders' Equity
Balance (in shares)	299.2	305.7
Balance at beginning of period	$ 0.3	$ 0.3
Retirement of treasury stock (in shares)	(0.8)	(4.2)
Stock options exercised (in shares)	1.0	0.6
Balance (in shares)	299.4	302.1
Balance at end of period	$ 0.3	$ 0.3
Additional Paid-In Capital
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period	1,433.2	1,249.0
Stock options exercised	37.6	20.7
Stock-based compensation expense	14.4	12.7
Balance at end of period	1,485.2	1,282.4
Retained Earnings
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period	3,028.7	2,941.5
Net income	267.5	265.6
Retirement of treasury stock	(72.4)	(382.0)
Stock options exercised	(13.2)
Dividends declared	(68.5)	(57.4)
Balance at end of period	3,142.1	2,770.9
Accumulated Other Comprehensive Loss
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period	(390.2)	(201.0)
Other comprehensive (loss) income	5.4	61.3
Balance at end of period	(384.8)	(139.7)
Treasury Stock
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period	$ (55.0)
Balance (in shares)	(0.7)
Purchase of treasury stock	$ (160.0)	$ (382.0)
Purchase of treasury stock (in shares)	(1.8)	(4.2)
Retirement of treasury stock	$ 72.4	$ 382.0
Retirement of treasury stock (in shares)	0.8	4.2
Stock options exercised	$ 22.9
Stock options exercised (in shares)	0.3
Balance at end of period	$ (119.7)
Balance (in shares)	(1.4)
Noncontrolling Interests
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period	$ 47.2	$ 53.6
Net income	2.4	2.7
Other comprehensive (loss) income	0.9	1.5
Acquisition resulting in noncontrolling interest		0.1
Distributions to shareholders of noncontrolling interests	(3.2)	(3.9)
Balance at end of period	$ 47.3	54.0
Impact of ASU 2014-09
Increase (Decrease) In Shareholders' Equity
Cumulative effect of adoption of revenue recognition standard		3.2
Impact of ASU 2014-09 | Retained Earnings
Increase (Decrease) In Shareholders' Equity
Cumulative effect of adoption of revenue recognition standard		$ 3.2