Acquisitions and Discontinued Operations Divestitures and Discontinued Operations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended					3 Months Ended		6 Months Ended	12 Months Ended	3 Months Ended			12 Months Ended	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012		Jun. 30, 2013	Jun. 30, 2012		Dec. 31, 2012		Jun. 30, 2013 FTC Natural Gas Pipeline Disposal Group [Member]	Jun. 30, 2012 FTC Natural Gas Pipeline Disposal Group [Member]	Jun. 30, 2012 FTC Natural Gas Pipeline Disposal Group [Member]	Dec. 31, 2012 KMP FTC Natural Gas Pipelines [Member]	Mar. 31, 2013 Express Pipeline System [Member]	Mar. 14, 2013 Express Pipeline System [Member]	Dec. 31, 2012 Express Pipeline System [Member]	Dec. 31, 2012 Loss on sale and the remeasurement of FTC Natural Gas Pipelines disposal group to fair value [Member] KMP FTC Natural Gas Pipelines [Member]	Jun. 30, 2013 Final consideration with Tallgrass [Member] KMP FTC Natural Gas Pipelines [Member]	Mar. 14, 2013 Express Pipeline System [Member]	Jun. 30, 2013 Copano Energy, LLC [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity Method Investment, Ownership Percentage																		33.33333%
Proceeds from sale of investments in Express pipeline system				$ 403	$ 0								$ 403
Loss on remeasurement of FTC Natural Gas Pipelines disposal group to fair value	0	327	[1]	2	649	[1]						829				649	2
Operating revenues										62	133
Operating expenses										(34)	(71)
Depreciation and amortization										0	(7)
Earnings from equity investments										20	42
Interest income and Other, net										0	1
Earnings from discontinued operations									48		98
Gain on Sale of Investments	0	0	[1]	225	0	[1]							225
Tax expense on sale of investments													84
Equity Method Investments														67	65
Related Party Transaction, Due from (to) Related Party, Noncurrent														110	114
Assets Held-for-sale, Current	32			32			211	[1]							179
Cash Acquired from Acquisition																			$ 29

[1] Retrospectively adjusted as discussed in Note 1.