Debt (Senior Notes Carrying Values) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Carrying values of the entity's senior notes
Long-term debt	$ 14,297.9	$ 6,265.7
1.900% senior notes due 2017
Carrying values of the entity's senior notes
Long-term debt	$ 503.0	501.0
Interest rate (as a percentage)	1.90%
2.125% senior notes due 2018
Carrying values of the entity's senior notes
Long-term debt	$ 999.9	0.0
Interest rate (as a percentage)	2.125%
2.300% senior notes due 2018
Carrying values of the entity's senior notes
Long-term debt	$ 403.8	401.2
Interest rate (as a percentage)	2.30%
2.250% senior notes due 2019
Carrying values of the entity's senior notes
Long-term debt	$ 511.3	502.5
Interest rate (as a percentage)	2.25%
2.875% senior notes due 2020
Carrying values of the entity's senior notes
Long-term debt	$ 1,497.4	0.0
Interest rate (as a percentage)	2.875%
3.950% senior notes due 2020
Carrying values of the entity's senior notes
Long-term debt	$ 514.6	502.8
Interest rate (as a percentage)	3.95%
3.250% senior notes due 2022
Carrying values of the entity's senior notes
Long-term debt	$ 1,032.3	1,010.2
Interest rate (as a percentage)	3.25%
3.550% senior notes due 2022
Carrying values of the entity's senior notes
Long-term debt	$ 997.3	0.0
Interest rate (as a percentage)	3.55%
4.000% senior notes due 2023
Carrying values of the entity's senior notes
Long-term debt	$ 722.2	708.5
Interest rate (as a percentage)	4.00%
3.625% senior notes due 2024
Carrying values of the entity's senior notes
Long-term debt	$ 1,003.4	996.8
Interest rate (as a percentage)	3.625%
3.875% senior notes due 2025
Carrying values of the entity's senior notes
Long-term debt	$ 2,476.1	0.0
Interest rate (as a percentage)	3.875%
5.700% senior notes due 2040
Carrying values of the entity's senior notes
Long-term debt	$ 249.6	249.5
Interest rate (as a percentage)	5.70%
5.250% senior notes due 2043
Carrying values of the entity's senior notes
Long-term debt	$ 396.7	396.7
Interest rate (as a percentage)	5.25%
4.625% senior notes due 2044
Carrying values of the entity's senior notes
Long-term debt	$ 996.5	996.5
Interest rate (as a percentage)	4.625%
5.000% senior notes due 2045
Carrying values of the entity's senior notes
Long-term debt	$ 1,993.8	$ 0.0
Interest rate (as a percentage)	5.00%