Sale of Accounts Receivable (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Accounts Receivable Securitization Programs [Line Items]
Proceeds from Sale and Collection of Receivables			$ 30,300	$ 23,700
Collections applied to deferred consideration			29,900	22,400
Cash payments received in exchange for the transfer of accounts receivable	$ 2,200		2,200		$ 2,100
Proceeds from transfer of receivables	1,100		1,100		1,600
Deferred receivables consideration	1,067		1,067		$ 511
Loss on transfer of accounts receivables to purchasers	1	$ 2	3	$ 4
Accounts Receivable Securitization Facility [Member]
Accounts Receivable Securitization Programs [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,600		1,600
Accounts Receivable Securitization Facility [Member] | Program [Member]
Accounts Receivable Securitization Programs [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,300		1,300
Accounts Receivable Securitization Facility [Member] | Second Program [Member]
Accounts Receivable Securitization Programs [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 300		$ 300