Other Property and Equipment - Narrative (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Property, Plant and Equipment [Line Items]
Net gains (losses) on sales of fixed assets	$ (86)	$ (132)	$ (201)	$ (290)
Reclassification from held for sale to held for use	116		116
Compressor [Member] | Hilcorp Energy [Member]
Property, Plant and Equipment [Line Items]
Equipment, Number of Units	61
Proceeds from Sale of Property, Plant, and Equipment	19
Net gains (losses) on sales of fixed assets	6
Compressor [Member] | Exterran Partners L.P. [Member]
Property, Plant and Equipment [Line Items]
Equipment, Number of Units	162		499
Proceeds from Sale of Property, Plant, and Equipment	133		495
Net gains (losses) on sales of fixed assets	68		(161)
Compressor [Member] | Access Midstream Partners, L.P. [Member]
Property, Plant and Equipment [Line Items]
Equipment, Number of Units			102
Proceeds from Sale of Property, Plant, and Equipment			159
Net gains (losses) on sales of fixed assets			(24)
Gathering and Processing Equipment [Member]
Property, Plant and Equipment [Line Items]
Net gains (losses) on sales of fixed assets	(5)	(132)	8	(311)
Gathering and Processing Equipment [Member] | SemGroup Corporation [Member]
Property, Plant and Equipment [Line Items]
Proceeds from Sale of Property, Plant, and Equipment		306
Net gains (losses) on sales of fixed assets	141
Gathering and Processing Equipment [Member] | Granite Wash Midstream Gas Services, L.L.C. [Member]
Property, Plant and Equipment [Line Items]
Proceeds from Sale of Property, Plant, and Equipment				252
Net gains (losses) on sales of fixed assets				(105)
Gathering and Processing Equipment [Member] | Sale to Western Gas Partners, LP [Member]
Property, Plant and Equipment [Line Items]
Proceeds from Sale of Property, Plant, and Equipment				134
Net gains (losses) on sales of fixed assets				(55)
Exploration and Production Equipment [Member]
Property, Plant and Equipment [Line Items]
Proceeds from Sale of Property, Plant, and Equipment			44
Net gains (losses) on sales of fixed assets	0	0	(7)	1
Crude Oil Hauling Equipment [Member]
Property, Plant and Equipment [Line Items]
Net gains (losses) on sales of fixed assets			23
Drilling Rigs [Member]
Property, Plant and Equipment [Line Items]
Equipment, Number of Units		8	14
Proceeds from Sale of Property, Plant, and Equipment			14
Net gains (losses) on sales of fixed assets			$ (14)