Borrowings and Contractual Commitments Contractual Commitments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014
Long-term Purchase Commitment [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 205
Capital Lease Obligations, Current	2
Purchase Obligation, Due in Next Twelve Months	421
Contractual Obligation, Due in Next Twelve Months	628
Operating Leases, Future Minimum Payments, Due in Two and Three Years	384
Capital Leases, Future Minimum Payments Due in Two and Three Years	3
Purchase Obligation, Due in Second and Third Year	38
Contractual Obligation, Due in Second and Third Year	425
Operating Leases, Future Minimum Payments, Due in Four and Five Years	194
Capital Leases, Future Minimum Payments Due in Four and Five Years	4
Purchase Obligation, Due in Fourth and Fifth Year	3
Contractual Obligation, Due in Fourth and Fifth Year	201
Operating Leases, Future Minimum Payments, Due Thereafter	328
Capital Leases, Future Minimum Payments Due Thereafter	0
Purchase Obligation, Due after Fifth Year	0
Contractual Obligation, Due after Fifth Year	328
Operating Leases, Future Minimum Payments Due	1,111
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments	9
Purchase Obligation	462
Contractual Obligation	$ 1,582