Other Property and Equipment Other Property and Equipment - Held for Use and Useful Life Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Buildings and Improvements, Gross	$ 1,119	$ 1,209
Capitalized Computer Software, Gross	337	318
Natural Gas Compressors, Gross	251	483
Land, Gross	139	289
Gathering Systems and Treating Plants, Gross	2	214
Other Property, Plant and Equipment, Miscellaneous	205	414
Other Property and Equipment, Gross	2,053	2,927
Property, Plant and Equipment, Other, Accumulated Depreciation	(632)	(813)
Property, Plant and Equipment, Other, Net	$ 1,421	$ 2,114
Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	10 – 39
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	5
Natural Gas Compressor [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	3 – 20
Gas Gathering and Processing Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	20
Property, Plant and Equipment, Other Types [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	2 – 20