Sale of Accounts Receivable (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Accounts Receivable Securitization Programs [Line Items]
Proceeds from Sale and Collection of Receivables	$ 11,200,000,000	$ 10,600,000,000
Collections applied to deferred consideration	11,000,000,000	10,600,000,000
Cash payments received in exchange for the transfer of accounts receivable	1,900,000,000		2,100,000,000
Proceeds from transfer of receivables	1,300,000,000		1,600,000,000
Deferred receivables consideration	614,000,000		511,000,000
Loss on transfer of accounts receivables to purchasers	1,000,000	1,000,000
Accounts Receivable Securitization Facility [Member]
Accounts Receivable Securitization Programs [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,500,000,000
Accounts Receivable Securitization Facility [Member] | Program [Member]
Accounts Receivable Securitization Programs [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,200,000,000
Accounts Receivable Securitization Facility [Member] | Second Program [Member]
Accounts Receivable Securitization Programs [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 300,000,000