Contingencies and Commitments (Schedule of Future Minimum Lease Payments On Operating Leases) Table (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 181
Operating Leases, Future Minimum Payments, Due in Two Years	220
Operating Leases, Future Minimum Payments, Due in Three Years	99
Operating Leases, Future Minimum Payments, Due in Four Years	182
Operating Leases, Future Minimum Payments, Due in Five Years	47
Operating Leases, Future Minimum Payments, Due Thereafter	39
Operating Leases, Future Minimum Payments Due	768
Drilling Rigs And Equipment
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	93
Operating Leases, Future Minimum Payments, Due in Two Years	82
Operating Leases, Future Minimum Payments, Due in Three Years	37
Operating Leases, Future Minimum Payments, Due in Four Years	68
Operating Leases, Future Minimum Payments, Due in Five Years	21
Operating Leases, Future Minimum Payments, Due Thereafter	6
Operating Leases, Future Minimum Payments Due	307
Natural Gas Compressors [Member]
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	71
Operating Leases, Future Minimum Payments, Due in Two Years	125
Operating Leases, Future Minimum Payments, Due in Three Years	51
Operating Leases, Future Minimum Payments, Due in Four Years	105
Operating Leases, Future Minimum Payments, Due in Five Years	23
Operating Leases, Future Minimum Payments, Due Thereafter	30
Operating Leases, Future Minimum Payments Due	405
Property, Plant and Equipment, Other Types
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	17
Operating Leases, Future Minimum Payments, Due in Two Years	13
Operating Leases, Future Minimum Payments, Due in Three Years	11
Operating Leases, Future Minimum Payments, Due in Four Years	9
Operating Leases, Future Minimum Payments, Due in Five Years	3
Operating Leases, Future Minimum Payments, Due Thereafter	3
Operating Leases, Future Minimum Payments Due	$ 56