Debt (Senior Notes Carrying Values) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Carrying values of the entity's senior notes
Long-term debt	$ 14,312.1	$ 14,161.4
1.900% senior notes due 2017
Carrying values of the entity's senior notes
Long-term debt	$ 501.3	499.9
Interest rate (as a percentage)	1.90%
2.125% senior notes due 2018
Carrying values of the entity's senior notes
Long-term debt	$ 997.3	996.7
Interest rate (as a percentage)	2.125%
2.300% senior notes due 2018
Carrying values of the entity's senior notes
Long-term debt	$ 402.5	400.2
Interest rate (as a percentage)	2.30%
2.250% senior notes due 2019
Carrying values of the entity's senior notes
Long-term debt	$ 511.9	502.6
Interest rate (as a percentage)	2.25%
2.875% senior notes due 2020
Carrying values of the entity's senior notes
Long-term debt	$ 1,491.8	1,490.9
Interest rate (as a percentage)	2.875%
3.950% senior notes due 2020
Carrying values of the entity's senior notes
Long-term debt	$ 521.4	504.9
Interest rate (as a percentage)	3.95%
3.250% senior notes due 2022
Carrying values of the entity's senior notes
Long-term debt	$ 1,060.1	1,010.5
Interest rate (as a percentage)	3.25%
3.550% senior notes due 2022
Carrying values of the entity's senior notes
Long-term debt	$ 992.9	992.4
Interest rate (as a percentage)	3.55%
4.000% senior notes due 2023
Carrying values of the entity's senior notes
Long-term debt	$ 746.7	706.0
Interest rate (as a percentage)	4.00%
3.625% senior notes due 2024
Carrying values of the entity's senior notes
Long-term debt	$ 1,001.6	994.9
Interest rate (as a percentage)	3.625%
3.875% senior notes due 2025
Carrying values of the entity's senior notes
Long-term debt	$ 2,483.6	2,461.8
Interest rate (as a percentage)	3.875%
5.700% senior notes due 2040
Carrying values of the entity's senior notes
Long-term debt	$ 247.2	247.2
Interest rate (as a percentage)	5.70%
5.250% senior notes due 2043
Carrying values of the entity's senior notes
Long-term debt	$ 392.9	392.8
Interest rate (as a percentage)	5.25%
4.625% senior notes due 2044
Carrying values of the entity's senior notes
Long-term debt	$ 986.7	986.6
Interest rate (as a percentage)	4.625%
5.000% senior notes due 2045
Carrying values of the entity's senior notes
Long-term debt	$ 1,974.2	$ 1,974.0
Interest rate (as a percentage)	5.00%