Other Property and Equipment Other Property and Equipment - Net (Gains) Losses on Sales of Fixed Assets Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Net (gains) losses on sales of fixed assets	$ (12)	$ 4	$ (199)
Buildings and land [Member]
Property, Plant and Equipment [Line Items]
Net (gains) losses on sales of fixed assets	(1)	3	(2)
Natural Gas Compressor [Member]
Property, Plant and Equipment [Line Items]
Net (gains) losses on sales of fixed assets	(10)	0	(195)
Gas Gathering and Processing Equipment [Member]
Property, Plant and Equipment [Line Items]
Net (gains) losses on sales of fixed assets	0	1	8
Exploration and Production Equipment [Member]
Property, Plant and Equipment [Line Items]
Net (gains) losses on sales of fixed assets	0	0	(7)
Other Assets [Member]
Property, Plant and Equipment [Line Items]
Net (gains) losses on sales of fixed assets	$ (1)	$ 0	$ (3)