Regulatory Matters Regulatory Assets and Liabilities (Details) (USD $)	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2005	Sep. 30, 2011	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2004	Mar. 31, 2004
Schedule Of Regulatory Assets And Liabilities [Line Items]
Total regulatory assets			$ 2,999,000,000		$ 3,388,000,000
Total regulatory liabilities			509,000,000		473,000,000
Total regulatory assets and liabilities, net			2,490,000,000		2,915,000,000
Amount of allowed equity return on the true-up balance that has not been recognized			508,000,000
Amount of allowed equity return on the true-up balance that was recognized in the period			45,000,000		47,000,000		21,000,000
Remaining amounts of regulatory assets for which no return on investment during recovery period is provided			5,000,000		14,000,000
Resolution of True-Up Appeal [Abstract]
Initial amount of true-up application									3,700,000,000
Amount awarded in final true-up order by the Texas Utility Commission								2,300,000,000
Net after-tax extraordinary gain (loss)	(947,000,000)	598,000,000	0		0		598,000,000
Extraordinary Item, Gain (Loss), Gross		921,000,000
Tax Effect of Extraordinary Item, Gain (Loss)		232,000,000
Return on true-up balance		352,000,000	0		0		352,000,000
Return on true-up balance after tax		229,000,000
Equity Return portion of Recoverable True-Up Balance pre-tax							405,000,000
Equity Return portion of Recoverable True-Up Balance after-tax							263,000,000
Securitized regulatory asset [Member]
Schedule Of Regulatory Assets And Liabilities [Line Items]
Total regulatory assets			3,179,000,000		3,545,000,000
Unrecognized equity return [Member]
Schedule Of Regulatory Assets And Liabilities [Line Items]
Total regulatory assets			(508,000,000)	[1]	(553,000,000)	[1]
Unamortized loss on reacquired debt [Member]
Schedule Of Regulatory Assets And Liabilities [Line Items]
Total regulatory assets			111,000,000		119,000,000
Pension and postretirement-related regulatory asset [Member]
Schedule Of Regulatory Assets And Liabilities [Line Items]
Total regulatory assets			90,000,000	[2]	165,000,000	[2]
Other long-term regulatory assets [Member]
Schedule Of Regulatory Assets And Liabilities [Line Items]
Total regulatory assets			127,000,000	[3]	112,000,000	[3]
Estimated removal costs [Member]
Schedule Of Regulatory Assets And Liabilities [Line Items]
Total regulatory liabilities			349,000,000		346,000,000
Other long-term regulatory liabilities [Member]
Schedule Of Regulatory Assets And Liabilities [Line Items]
Total regulatory liabilities			$ 160,000,000		$ 127,000,000

[1] As of December 31, 2013, CenterPoint Houston has not recognized an allowed equity return of $508 million because such return will be recognized as it is recovered in rates. During the years ended December 31, 2013, 2012 and 2011, CenterPoint Houston recognized approximately $45 million, $47 million and $21 million, respectively, of the allowed equity return.

[2] CenterPoint Houston’s actuarially determined pension and other postemployment expense in excess of the amount being recovered through rates is being deferred for rate making purposes. Deferred pension and other postemployment expenses of $5 million and $14 million as of December 31, 2013 and 2012, respectively, were not earning a return.

[3] Other regulatory assets that are not earning a return were not material as of December 31, 2013 and 2012.