Derivative Instruments and Hedging Activities (Details) (USD $) In Millions, unless otherwise specified						3 Months Ended		12 Months Ended															12 Months Ended		1 Months Ended				1 Months Ended			3 Months Ended	1 Months Ended
	Mar. 31, 2013 2.450% senior notes due 2015	Mar. 31, 2013 1.900% senior notes due 2017	Mar. 31, 2013 3.950% senior notes due 2020	Mar. 31, 2013 3.250% senior notes due 2022	Mar. 31, 2013 5.700% senior notes due 2040	Mar. 31, 2013 Foreign currency forward contracts	Mar. 31, 2013 Designated as hedging instruments Foreign currency forward contracts	Dec. 31, 2012 Designated as hedging instruments Foreign currency forward contracts	Mar. 31, 2013 Designated as hedging instruments Foreign currency forward contracts Australian Dollar	Dec. 31, 2012 Designated as hedging instruments Foreign currency forward contracts Australian Dollar	Mar. 31, 2013 Designated as hedging instruments Foreign currency forward contracts British Pound	Dec. 31, 2012 Designated as hedging instruments Foreign currency forward contracts British Pound	Mar. 31, 2013 Designated as hedging instruments Foreign currency forward contracts Canadian Dollar	Dec. 31, 2012 Designated as hedging instruments Foreign currency forward contracts Canadian Dollar	Mar. 31, 2013 Designated as hedging instruments Foreign currency forward contracts Euro	Dec. 31, 2012 Designated as hedging instruments Foreign currency forward contracts Euro	Mar. 31, 2013 Designated as hedging instruments Foreign currency forward contracts Japanese Yen	Dec. 31, 2012 Designated as hedging instruments Foreign currency forward contracts Japanese Yen	Mar. 31, 2013 Designated as hedging instruments Foreign currency option contracts Purchased Put	Dec. 31, 2012 Designated as hedging instruments Foreign currency option contracts Purchased Put	Mar. 31, 2013 Designated as hedging instruments Foreign currency option contracts Written Call	Dec. 31, 2012 Designated as hedging instruments Foreign currency option contracts Written Call	Dec. 31, 2012 Designated as hedging instruments Treasury rate locks	Mar. 31, 2013 Designated as hedging instruments Treasury rate locks	Apr. 30, 2013 Designated as hedging instruments Interest rate swap contracts	Mar. 31, 2013 Designated as hedging instruments Interest rate swap contracts	Dec. 31, 2012 Designated as hedging instruments Interest rate swap contracts	Mar. 31, 2013 Designated as hedging instruments Interest rate swap contracts 2.450% senior notes due 2015	Apr. 30, 2013 Designated as hedging instruments Interest rate swap contracts 1.900% senior notes due 2017	Mar. 31, 2013 Designated as hedging instruments Interest rate swap contracts 1.900% senior notes due 2017	Dec. 31, 2012 Designated as hedging instruments Interest rate swap contracts 1.900% senior notes due 2017	Mar. 31, 2013 Designated as hedging instruments Interest rate swap contracts 3.950% senior notes due 2020	Apr. 30, 2013 Designated as hedging instruments Interest rate swap contracts 3.250% senior notes due 2022	Mar. 31, 2013 Designated as hedging instruments Interest rate swap contracts 3.250% senior notes due 2022	Dec. 31, 2012 Designated as hedging instruments Interest rate swap contracts 3.250% senior notes due 2022	Mar. 31, 2013 Not designated as hedging instruments Foreign currency forward contracts	Dec. 31, 2012 Not designated as hedging instruments Foreign currency forward contracts	Mar. 31, 2013 Not designated as hedging instruments Foreign currency option contracts Purchased Put	Dec. 31, 2012 Not designated as hedging instruments Foreign currency option contracts Purchased Put	Mar. 31, 2013 Not designated as hedging instruments Foreign currency option contracts Written put	Dec. 31, 2012 Not designated as hedging instruments Foreign currency option contracts Written put
Summary of Derivative Instruments
Period to settlement dates of derivatives is within this period						3 years	36 months	36 months
Notional amount							$ 1,915.0	$ 1,422.9	$ 6.2	$ 5.1	$ 87.7	$ 77.9	$ 105.2	$ 134.4	$ 1,322.4	$ 969.3	$ 393.5	$ 236.2	$ 139.0	$ 228.8	$ 144.6	$ 235.9				$ 1,900.0	$ 300.0	$ 400.0		$ 500.0	$ 100.0			$ 1,000.0	$ 200.0			$ 131.0	$ 160.5	$ (131.0)	$ (216.0)
Aggregate notional amount of foreign currency forward non-designated hedging contracts																																				971.2	795.4
Derivative settlement losses																							35.3
Amount outstanding																								0
Interest rate (as a percent)	2.45%	1.90%	3.95%	3.25%	5.70%
Amount settled																									800.0				400.0			400.0	400.0
Proceeds from settlement of interest rate swap contracts																													$ 1.7			$ 2.8	$ 4.5