Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 MBbls MMBTU	Dec. 31, 2012	Dec. 31, 2011
Future minimum payments under non-cancellable agreements
Natural Gas Commitments Current	11,250,000
2014	$ 156
2015	110
2016	88
2017	86
2018	76
Thereafter	121
Total minimum future payments	637
Delivery Commitments, Current	7,483,000
Natural Gas Commitments Due In Two Years	0
Delivery Commitments, Due In Two Years	7,483,000
Natural Gas Commitments Due In Three Years	0
Delivery Commitments, Due In Three Years	9,190,000
Natural Gas Delivery Commitments Due In Four Years	0
Delivery Commitments, Due In Four Years	13,870,000
Natural Gas Delivery Commitments Due In Five Years	0
Delivery Commitments, Due In Five Years	13,870,000
Natural Gas Commitments Due Thereafter	0
Delivery Commitments, Due Thereafter	50,748,000
Total Natural Gas Commitments	11,250,000
Total Delivery Commitments	102,644,000
Commitments and Contingencies (Textuals) [Abstract]
Rent expense under lease commitments	18	17	14
Operating Leases, discontinuing Operations	5
Other Agreements, Discontinued Operations	245
Firm Transportation [Member]
Future minimum payments under non-cancellable agreements
2014	78
2015	76
2016	73
2017	71
2018	62
Thereafter	85
Total minimum future payments	445
Operating Leases [Member]
Future minimum payments under non-cancellable agreements
2014	17
2015	18
2016	15
2017	15
2018	14
Thereafter	36
Total minimum future payments	115
Other Commitments [Member]
Future minimum payments under non-cancellable agreements
2014	61
2015	16
2016	0
2017	0
2018	0
Thereafter	0
Total minimum future payments	$ 77