Reduction In Workforce (Summary Of Restructuring Charges) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2016
Restructuring Cost and Reserve [Line Items]
Severance (including payroll taxes)		$ 29
Total restructuring charges	$ 11	75
Exploration and Production [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	11	72
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)	2	44
Stock-based compensation	6	24
Pension and other postretirement benefits	3	3
Other benefits		3
Outplacement services, other		1
Total restructuring charges	11	75
Workforce Reduction [Member] | Executive Management [Member]
Restructuring Cost and Reserve [Line Items]
Severance (including payroll taxes)	1	1
Stock-based compensation	3	3
Workforce Reduction [Member] | Exploration and Production [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	11	72
Workforce Reduction [Member] | Midstream Services [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 1	$ 3