Debt, Credit Facilities, and Commitments and Contingencies (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Commercial paper	Dec. 31, 2012 Commercial paper	Nov. 30, 2012 Commercial paper	Dec. 31, 2013 Unsecured bank credit facility
Short-Term Borrowings
Lease expense	$ 107,000,000
Short-Term Borrowings
Short-term borrowings	413,000,000	1,020,000,000	400,000,000	1,000,000,000	1,000,000,000
Weighted-average interest rate (as a percent)			0.20%	0.40%
Borrowing capacity						2,000,000,000
Operating leases
2014	87,000,000
2015	79,000,000
2016	71,000,000
2017	62,000,000
2018	46,000,000
Thereafter	530,000,000
Total obligations and commitments	875,000,000
Debt maturities and capital leases
2014	18,000,000
2015	4,012,000,000
2016	11,000,000
2017	4,008,000,000
2018	1,006,000,000
Thereafter	5,743,000,000
Total obligations and commitments	14,798,000,000
Fair value hedges and unamortized bond discounts	(488,000,000)
Total long-term debt and lease obligations	$ 14,310,000,000	$ 14,652,000,000