Borrowings and Contractual Commitments Contractual Commitments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Long-term Purchase Commitment [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 214
Capital Lease Obligations, Current	1	[1]
Purchase Obligation, Due in Next Twelve Months	96	[2]
Contractual Obligation, Due in Next Twelve Months	311
Operating Leases, Future Minimum Payments, Due in Two and Three Years	387
Capital Leases, Future Minimum Payments Due in Two and Three Years	3	[1]
Purchase Obligation, Due in Second and Third Year	469	[2]
Contractual Obligation, Due in Second and Third Year	859
Operating Leases, Future Minimum Payments, Due in Four and Five Years	331
Capital Leases, Future Minimum Payments Due in Four and Five Years	3	[1]
Purchase Obligation, Due in Fourth and Fifth Year	222	[2]
Contractual Obligation, Due in Fourth and Fifth Year	556
Operating Leases, Future Minimum Payments, Due Thereafter	377
Capital Leases, Future Minimum Payments, Due in Rolling after Year Five	4	[1]
Purchase Obligation, Due after Fifth Year	0	[2]
Contractual Obligation, Due after Fifth Year	381
Operating Leases, Future Minimum Payments Due	1,309
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments	11	[1]
Purchase Obligation	787	[2]
Contractual Obligation	$ 2,107

[1] Amounts do not include accrued interest.

[2] Includes contracts with a minimum annual payment of $5 million or more.