Commitments And Contingencies (Schedule Of Commitments And Contingencies) (Details) $ in Millions	Dec. 31, 2016 USD ($)
Purchase Obligations [Member]
Long Term Purchase Commitment [Line Items]
2017	$ 609
2018	649
2019	762
2020	748
2021	181
Total	2,949
Drilling And Facility Obligations [Member]
Long Term Purchase Commitment [Line Items]
2017	76
2018	66
2019	67
2020	57
2021	37
Thereafter	85
Total	388
Operational Agreements [Member]
Long Term Purchase Commitment [Line Items]
2017	1,145
2018	1,134
2019	627
2020	457
2021	285
Thereafter	2,667
Total	6,315
Office And Equipment Leases [Member]
Long Term Purchase Commitment [Line Items]
2017	50
2018	85
2019	83
2020	59
2021	39
Thereafter	55
Total	371
EnLink Obligations [Member]
Long Term Purchase Commitment [Line Items]
2017	50
2018	51
2019	33
2020	18
2021	17
Thereafter	102
Total	$ 271