Bank Financing and Debt (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
Senior debt (1.95% - 7.875% due 2017 - 2045)	$ 8,851,000,000	$ 8,850,000,000
Obligations under capital leases	72,000,000	75,000,000
Total debt	8,953,000,000	9,375,000,000
Current portion of long-term debt	23,000,000	23,000,000
Total long-term debt, net of current portion	8,900,000,000	8,902,000,000
Current portion of long-term debt classified as long-term debt reflecting Company's intent and ability to refinance on a long-term basis	400,000,000
Net unamortized discount on senior debt	50,000,000	52,000,000
Unamortized deferred financing costs	42,000,000	43,000,000
Increase in carrying value of debt relating to previously settled fair value hedges	4,000,000	5,000,000
Commercial paper	30,000,000	$ 450,000,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity under credit facility	2,500,000,000.0
Availability under credit facility	2,490,000,000
Amount borrowed under credit facility	$ 0
Revolving Credit Facility [Member] | Maximum Consolidated Leverage Ratio [Member]
Line of Credit Facility [Line Items]
Credit facility, covenant description	4.5x
Revolving Credit Facility [Member] | Consolidated Leverage Ratio [Member]
Line of Credit Facility [Line Items]
Credit facility, covenant compliance	2.8x
Commercial Paper [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity under credit facility	$ 2,500,000,000.0
Weighted average interest rate	1.20%	0.98%