Commitments and Contingencies (Schedule of Annual Rentals on a Lease Basis) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2012
Operating Leases, Future Minimum Payments Due, Next Twelve Months $ 206
Operating Leases, Future Minimum Payments Due in Two Years 168
Operating Leases, Future Minimum Payments Due in Three Years 139
Operating Leases, Future Minimum Payments Due in Four Years 109
Operating Leases, Future Minimum Payments Due in Five Years 75
Operating Leases, Future Minimum Payments Due Thereafter $ 265