Reduction In Workforce (Summary Of Restructuring Charges) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 64
Exploration and Production [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	61
Midstream Services [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	3
Workforce Reduction [Member]
Restructuring Cost and Reserve [Line Items]
Severance (including payroll taxes)	42
Stock-based compensation	18
Pension and other postretirement benefits	3
Outplacement services, other	1
Total restructuring charges	64
Workforce Reduction [Member] | Exploration and Production [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	61
Workforce Reduction [Member] | Midstream Services [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 3