Long-term Debt (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended								12 Months Ended				12 Months Ended				12 Months Ended				12 Months Ended								12 Months Ended		3 Months Ended	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2013 First mortgage bonds 9.15% due 2021(2)		Dec. 31, 2012 First mortgage bonds 9.15% due 2021(2)		Dec. 31, 2013 General mortgage bonds 2.25% to 6.95% due 2022 to 2042		Dec. 31, 2012 General mortgage bonds 2.25% to 6.95% due 2022 to 2042		Dec. 31, 2013 Pollution control bonds 4.25% to 5.60% due 2017 to 2027(3)		Dec. 31, 2012 Pollution control bonds 4.25% to 5.60% due 2017 to 2027(3)		Dec. 31, 2013 System restoration bonds 1.833% to 4.243% due 2014 to 2022		Dec. 31, 2012 System restoration bonds 1.833% to 4.243% due 2014 to 2022		Dec. 31, 2013 Transition bonds 0.90% to 5.302% due 2014 to 2024		Dec. 31, 2012 Transition bonds 0.90% to 5.302% due 2014 to 2024		Dec. 31, 2013 Other		Dec. 31, 2012 Other		Dec. 31, 2013 Revolving Credit Facility [Member]	Dec. 31, 2012 Revolving Credit Facility [Member]	Mar. 31, 2013 March 2013 [Member] CenterPoint Houston [Member] Bonds General Mortgage Due 2013 [Member]	Dec. 31, 2013 August 1st, 2013 [Member] CenterPoint Houston [Member] Notes Payable, Other Payables [Member]	Dec. 31, 2013 August 1st, 2013 [Member] CenterPoint Houston [Member] Bonds First Mortgage Due2015 Member [Member]	Dec. 31, 2013 August 1st, 2013 [Member] CenterPoint Energy [Member] Bonds Pollution Control Due2015 Member	Dec. 31, 2013 October 15th, 2013 [Member] CenterPoint Houston [Member] Bonds Pollution Control Due2015 Member	Dec. 31, 2013 October 15th, 2013 [Member] CenterPoint Houston [Member] Notes Payable, Other Payables [Member]	Dec. 31, 2013 October 15th, 2013 [Member] CenterPoint Energy [Member] Bonds Pollution Control Due2015 Member	Dec. 31, 2013 January 2014 [Member] CenterPoint Houston [Member] Bonds Pollution Control Due2017 [Member]	Dec. 31, 2013 February 2014 [Member] CenterPoint Houston [Member] Bonds Pollution Control Due2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum									2.25%				4.25%				1.833%				0.90%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum									6.95%				5.60%				4.243%				5.302%
Long-term Debt, Excluding Current Maturities	$ 4,641		$ 4,995		$ 102	[1]	$ 102	[1]	$ 1,312		$ 1,312		$ 183	[2]	$ 183	[2]	$ 463		$ 510		$ 2,583		$ 2,890		$ (2)		$ (2)
Long-term Debt, Current Maturities	354	[3]	897	[3]	0	[1],[3]	0	[1],[3]	0	[3]	450	[3]	0	[2],[3]	0	[2],[3]	47	[3]	46	[3]	307	[3]	401	[3]	0	[3]	0	[3]
Debt Instrument, Term	1 year
Extinguishment of Debt, Amount																															450	92	92	92	59	59	59	44	56
Debt Instrument, Interest Rate, Stated Percentage					9.15%																										5.70%	4.00%				4.00%		4.25%	5.60%
Extinguishment Of Debt Purchase Price Percentage Of Principal																																101.00%				101.00%		101.00%	101.00%
Debt Instrument, Maturity Date																																						Dec. 31, 2017	Dec. 31, 2027
Special purpose subsidiaries	4
Line of Credit Facility [Abstract]
Size of Credit Facility																													300	300
Loans Outstanding																													0	0
Letters of Credit Outstanding																													4	4
Line of Credit Facility, Interest Rate Description																													112.5
Percentage on limitation of debt to total capitalization under covenant (in hundredths)																													65.00%
Annual maturities of long-term debt [Abstract]
2014	354
2015	372
2016	391
2017	539
2018	434
Transition and system restoration bond principal repayments included in annual maturities [Abstract]
2014	354
2015	372
2016	391
2017	411
2018	434
Secured Debt					102				1,900
Replacement Fund Requirements	198
Sinking Fund Requirements	$ 1.6

[1] Debt issued as collateral is excluded from the financial statements because of the contingent nature of the obligation.

[2] These series of debt are collateralized by CenterPoint Houston’s general mortgage bonds.

[3] Includes amounts due or scheduled to be paid within one year of the date noted.