Debt (Long-Term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Aug. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term debt, net of discount	$ 14,250.4		$ 6,265.7
2.125% senior notes due 2018
Debt Instrument [Line Items]
Interest rate (as a percent)		2.125%
2.875% senior notes due 2020
Debt Instrument [Line Items]
Interest rate (as a percent)		2.875%
3.550% senior notes due 2022
Debt Instrument [Line Items]
Interest rate (as a percent)		3.55%
3.875% senior notes due 2025
Debt Instrument [Line Items]
Interest rate (as a percent)		3.875%
5.000% senior notes due 2045
Debt Instrument [Line Items]
Interest rate (as a percent)		5.00%
Senior Notes
Debt Instrument [Line Items]
Long-term debt, net of discount	$ 14,250.4		$ 6,265.7
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	$ 501.2		$ 501.0
Senior Notes | 2.125% senior notes due 2018
Debt Instrument [Line Items]
Interest rate (as a percent)	2.125%
Long-term debt, net of discount	$ 999.9		$ 0.0
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	$ 401.7		$ 401.2
Senior Notes | 2.250% senior notes due 2019
Debt Instrument [Line Items]
Interest rate (as a percent)	2.25%		2.25%
Long-term debt, net of discount	$ 505.1		$ 502.5
Senior Notes | 2.875% senior notes due 2020
Debt Instrument [Line Items]
Interest rate (as a percent)	2.875%
Long-term debt, net of discount	$ 1,497.5		$ 0.0
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	$ 507.1		$ 502.8
Senior Notes | 3.250% senior notes due 2022
Debt Instrument [Line Items]
Interest rate (as a percent)	3.25%
Long-term debt, net of discount	$ 1,016.1		$ 1,010.2
Senior Notes | 3.550% senior notes due 2022
Debt Instrument [Line Items]
Interest rate (as a percent)	3.55%		3.55%
Long-term debt, net of discount	$ 997.4		$ 0.0
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	$ 710.3		$ 708.5
Senior Notes | 3.625% senior notes due 2024
Debt Instrument [Line Items]
Interest rate (as a percent)	3.625%		3.625%
Long-term debt, net of discount	$ 1,001.7		$ 996.8
Senior Notes | 3.875% senior notes due 2025
Debt Instrument [Line Items]
Interest rate (as a percent)	3.875%
Long-term debt, net of discount	$ 2,475.6		$ 0.0
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	$ 249.6		$ 249.5
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		$ 396.7
Senior Notes | 4.625% senior notes due 2044
Debt Instrument [Line Items]
Interest rate (as a percent)	4.625%		4.625%
Long-term debt, net of discount	$ 996.6		$ 996.5
Senior Notes | 5.000% senior notes due 2045
Debt Instrument [Line Items]
Interest rate (as a percent)	5.00%
Long-term debt, net of discount	$ 1,993.9		$ 0.0