Acquisitions and Discontinued Operations Acquisitions (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended			6 Months Ended					3 Months Ended				6 Months Ended					3 Months Ended
	Jun. 30, 2013 Mcf MMcf	Jun. 30, 2012		Jun. 30, 2013 Mcf MMcf	Jun. 30, 2012		Jun. 30, 2013 March 2013 KMI Asset Drop Down [Member]	Mar. 01, 2013 March 2013 KMI Asset Drop Down [Member]	Jun. 30, 2012 Copano Energy, LLC [Member]	Jun. 30, 2013 Copano Energy, LLC [Member] mi	May 01, 2013 Copano Energy, LLC [Member]	Feb. 26, 2013 Common Unit [Member]	Jun. 30, 2013 Common Unit [Member] March 2013 KMI Asset Drop Down [Member]	Mar. 01, 2013 Common Unit [Member] March 2013 KMI Asset Drop Down [Member]	May 01, 2013 May 31, 2013 [Member] Common Unit [Member]	May 01, 2013 Eagle Ford Gathering LLC [Member] Copano Energy, LLC [Member]	May 01, 2013 May 31, 2013 [Member] Eagle Ford Gathering LLC [Member] Copano Energy, LLC [Member]	Jun. 30, 2013 Pre-tax [Member]	Jun. 30, 2013 Bcf/d [Member] Mcf	Jun. 30, 2013 Natural Gas Processing Plant [Member]	Jun. 30, 2013 Ector County, Texas [Member] Legado Resources [Member] acre MMcf	May 31, 2013 Ector County, Texas [Member] Legado Resources [Member] acre	May 31, 2013 Permian basin [Member] Legado Resources [Member]	May 31, 2013 Property, plant, and equipment [Member] Permian basin [Member] CO2 [Member] Legado Resources [Member]
Business Acquisition [Line Items]
Business Acquisition, Purchase Price Allocation, Current Assets										$ 217
Business acquisition, equity interest issued (in shares)									43,371,210				1,249,452
Business Acquisition, Cost of Acquired Entity, Cash Paid							6	994			5,200													285
Stock Issued During Period, Value, Acquisitions													108
Sale of Stock, Price Per Share												$ 86.35		$ 86.72
Business Acquisition, Purchase Price Allocation, Liabilities Assumed								557															18
Percent of acquired entity's debt included as part of purchase price								50.00%
Miles of pipe										6,900
Business acquisition, unit exchange ratio											0.4563
Natural gas transportation capacity																			2,700,000
Gas processing capacity	1,000,000			1,000,000
Gas treating capacity	315			315
Business Acquisition, Cost of Acquired Entity, percent unit for unit											100.00%
Common Units Issued											43,371,210
Business Acquisition, Cost of Acquired Entity, Equity Interests Issued and Issuable											3,733
Business Acquisition, Share Price															$ 86.08
Business Acquisition, Percent Acquired																50.00%	50.00%
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain	558	0	[1]	558	0	[1]												558
Business Acquisition, Purchase Price Allocation, Property, Plant and Equipment										2,753
Business Acquisition, Purchase Price Allocation, Investments										448
Business Acquisition, Purchase Price Allocation, Goodwill Amount										1,123
Business Acquisition, Purchase Price Allocation, Intangible Assets Other than Goodwill										1,350
Business Acquisition, Purchase Price Allocation, Other Assets										12
Business Acquisition, Purchase Price Allocation, Assets Acquired										5,903
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value										(704)
Business Acquisition, Purchase Price Allocation, Assets, Net										5,199
Business Acquisition, Purchase Price Allocation, Current Liabilities										(207)
Business Acquisition, Purchase Price Allocation, Other Liabilities										(7)
Business Acquisition, Purchase Price Allocation, Notes Payable and Long-term Debt										(1,252)
Consideration per unit										3,733
Finite-Lived Intangible Asset, Useful Life	25 years
Number of Facilities																				9
Gas and Oil Area, Developed, Gross																						6,000
Barrels of Oil																					1,250
Contract aquired in aquisition, amount of CO2 (Mmcf/d) to suppply																					150
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ 0	$ (279)	[1]	$ (2)	$ (551)	[1]

[1] Retrospectively adjusted as discussed in Note 1.