Sale of Accounts Receivable (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Accounts Receivable Securitization Programs [Line Items]
Receivables sold under securitization facility derecognized during the period	$ 2,000,000,000
Deferred receivables consideration	573,000,000		757,000,000
Cash payments received in exchange for the transfer of accounts receivable	1,400,000,000
Proceeds received in cash from transfers of receivables to purchasers	10,600,000,000	9,800,000,000
Loss on transfer of accounts receivables to purchasers	1,000,000	1,000,000
Maximum amount of facility provided under accounts receivable securitization program	1,500,000,000
Program [Member]
Accounts Receivable Securitization Programs [Line Items]
Maximum amount of facility provided under accounts receivable securitization program	1,100,000,000
Second Program [Member]
Accounts Receivable Securitization Programs [Line Items]
Maximum amount of facility provided under accounts receivable securitization program	$ 400,000,000