Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2013	$ 0
2014	0
2015	0
2016	0
2017	0
Operating lease rent expense	$ 1	$ 1	$ 1
Recovery of compensatory damages sought by plaintiffs	1000000000
Approximate number of gas market manipulation lawsuits naming CenterPoint Energy and/or Reliant Energy (in number of lawsuits)	30
Number of gas market manipulation lawsuits pending for CenterPoint and its affiliates (in number of lawsuits)	2

The total number of pending lawsuits related to gas market manipulation.

No definition available.

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- Definition

The total amount of gas market manipulation lawsuits filed against a company.

+ References

No definition available.

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- Definition

Rental expense incurred for leased assets including furniture and equipment which has not been recognized in costs and expenses applicable to sales and revenues; for example, cost of goods sold or other operating costs and expenses.

+ References

No definition available.

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Describes the form and magnitude of the award the plaintiff seeks in the legal matter, which may include an unspecified amount of money.

+ References

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Amount of required minimum rental payments maturing in the next fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

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Amount of required minimum rental payments maturing in the fifth fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

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Amount of required minimum rental payments maturing in the forth fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

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Amount of required minimum rental payments maturing in the third fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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Amount of required minimum rental payments maturing in the second fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

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