Debt (Long-Term Debt) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Long-term debt, net of discount	$ 6,265.7	$ 4,196.5
2.250% senior notes due 2019
Debt Instrument [Line Items]
Interest rate (as a percent)	2.25%
3.625% senior notes due 2024
Debt Instrument [Line Items]
Interest rate (as a percent)	3.625%
4.625% senior notes due 2044
Debt Instrument [Line Items]
Interest rate (as a percent)	4.625%
Senior Notes | 2.450% senior notes due 2015
Debt Instrument [Line Items]
Interest rate (as a percent)	2.45%	2.45%
Long-term debt, net of discount	0	513.9
Senior Notes | 1.900% senior notes due 2017
Debt Instrument [Line Items]
Interest rate (as a percent)	1.90%	1.90%
Long-term debt, net of discount	501.0	499.9
Senior Notes | 2.300% senior notes due 2018
Debt Instrument [Line Items]
Interest rate (as a percent)	2.30%	2.30%
Long-term debt, net of discount	401.2	399.0
Senior Notes | 2.250% senior notes due 2019
Debt Instrument [Line Items]
Interest rate (as a percent)	2.25%	0.00%
Long-term debt, net of discount	502.5	0
Senior Notes | 3.950% senior notes due 2020
Debt Instrument [Line Items]
Interest rate (as a percent)	3.95%	3.95%
Long-term debt, net of discount	502.8	484.6
Senior Notes | 3.250% senior notes due 2022
Debt Instrument [Line Items]
Interest rate (as a percent)	3.25%	3.25%
Long-term debt, net of discount	1,010.2	956.6
Senior Notes | 4.000% senior notes due 2023
Debt Instrument [Line Items]
Interest rate (as a percent)	4.00%	4.00%
Long-term debt, net of discount	708.5	696.3
Senior Notes | 3.625% senior notes due 2024
Debt Instrument [Line Items]
Interest rate (as a percent)	3.625%	0.00%
Long-term debt, net of discount	996.8	0
Senior Notes | 5.700% senior notes due 2040
Debt Instrument [Line Items]
Interest rate (as a percent)	5.70%	5.70%
Long-term debt, net of discount	249.5	249.6
Senior Notes | 5.250% senior notes due 2043
Debt Instrument [Line Items]
Interest rate (as a percent)	5.25%	5.25%
Long-term debt, net of discount	396.7	396.6
Senior Notes | 4.625% senior notes due 2044
Debt Instrument [Line Items]
Interest rate (as a percent)	4.625%	0.00%
Long-term debt, net of discount	$ 996.5	$ 0