Sale of Accounts Receivable (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Accounts Receivable Securitization Programs [Line Items]
Proceeds from Sale and Collection of Receivables			$ 20,800	$ 14,700
Collections applied to deferred consideration			20,600	13,600
Cash payments received in exchange for the transfer of accounts receivable	$ 2,000		2,000		$ 2,100
Proceeds from transfer of receivables	1,300		1,300		1,600
Deferred receivables consideration	703		703		$ 511
Loss on transfer of accounts receivables to purchasers	1	$ 1	2	$ 2
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