Shareholders' Equity and Noncontrolling Interests (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period			$ 4,043.4	$ 3,723.1
Net income	$ 287.8	$ 253.6	556.1	480.9
Other comprehensive (loss) income	(151.5)	62.1	(88.7)	129.2
Acquisition resulting in noncontrolling interest			0.3	0.8
Purchase of noncontrolling interest				(15.0)
Distributions to shareholders of noncontrolling interests			(7.1)	(4.2)
Purchase of treasury stock			(645.4)	(399.9)
Stock options exercised			51.2	74.4
Dividends declared	(69.0)	(48.8)	(126.4)	(97.8)
Stock-based compensation expense			26.0	24.4
Balance at end of period	$ 3,812.6	$ 3,915.9	$ 3,812.6	$ 3,915.9
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)			(7.3)	(5.7)
Stock options exercised (in shares)			1.3	2.6
Balance (in shares)	299.7	305.2	299.7	305.2
Balance at end of period	$ 0.3	$ 0.3	$ 0.3	$ 0.3
Additional Paid-In Capital
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period			1,249.0	1,020.9
Purchase of noncontrolling interest				(5.5)
Stock options exercised			51.2	74.4
Stock-based compensation expense			26.0	24.4
Balance at end of period	1,326.2	1,114.2	1,326.2	1,114.2
Retained Earnings
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period			2,941.5	3,122.7
Net income			550.4	476.4
Retirement of treasury stock			(645.4)	(399.9)
Dividends declared			(126.4)	(97.8)
Balance at end of period	2,723.3	3,101.4	2,723.3	3,101.4
Accumulated Other Comprehensive Loss
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period			(201.0)	(469.0)
Other comprehensive (loss) income			(87.7)	128.0
Balance at end of period	(288.7)	(341.0)	(288.7)	(341.0)
Treasury Stock
Increase (Decrease) In Shareholders' Equity
Purchase of treasury stock			(645.4)	(399.9)
Retirement of treasury stock			645.4	399.9
Noncontrolling Interests
Increase (Decrease) In Shareholders' Equity
Balance at beginning of period			53.6	48.2
Net income			5.7	4.5
Other comprehensive (loss) income			(1.0)	1.2
Acquisition resulting in noncontrolling interest			0.3	0.8
Purchase of noncontrolling interest				(9.5)
Distributions to shareholders of noncontrolling interests			(7.1)	(4.2)
Balance at end of period	51.5	$ 41.0	51.5	$ 41.0
Impact of ASU 2014-09
Increase (Decrease) In Shareholders' Equity
Cumulative effect of adoption of revenue recognition standard (Note 2)	3.2		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		$ 3.2