Fair Value Measurements (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Trading securities	$ 22	$ 523
Available-for-sale securities	133	132
Interest rate swap agreements	53	84
Other [assets]	17	71
Fair Value, Assets Measured on Recurring Basis, Total	225	810
Derivative component of prepaid forward sale agreements and indexed debt instruments	5	361
Contractual obligations	0	883
Contingent consideration	0	644
Other [liabilities]	86	8
Fair Value Liabilities Measured On Recurring Basis, Total	91	1,896
Fair Value, Inputs, Level 1 [Member]
Trading securities	22	523
Available-for-sale securities	0	1
Interest rate swap agreements	0	0
Other [assets]	0	0
Fair Value, Assets Measured on Recurring Basis, Total	22	524
Derivative component of prepaid forward sale agreements and indexed debt instruments	0	0
Contractual obligations	0	0
Contingent consideration	0	0
Other [liabilities]	0	0
Fair Value Liabilities Measured On Recurring Basis, Total	0	0
Fair Value, Inputs, Level 2 [Member]
Trading securities	0	0
Available-for-sale securities	123	121
Interest rate swap agreements	53	84
Other [assets]	5	64
Fair Value, Assets Measured on Recurring Basis, Total	181	269
Derivative component of prepaid forward sale agreements and indexed debt instruments	5	361
Contractual obligations	0	0
Contingent consideration	0	0
Other [liabilities]	86	8
Fair Value Liabilities Measured On Recurring Basis, Total	91	369
Fair Value, Inputs, Level 3 [Member]
Trading securities	0	0
Available-for-sale securities	10	10
Interest rate swap agreements	0	0
Other [assets]	12	7
Fair Value, Assets Measured on Recurring Basis, Total	22	17
Derivative component of prepaid forward sale agreements and indexed debt instruments	0	0
Contractual obligations	0	883
Contingent consideration	0	644
Other [liabilities]	0	0
Fair Value Liabilities Measured On Recurring Basis, Total	$ 0	$ 1,527