Unaudited Quarterly Information (Details) - USD ($) $ in Millions	3 Months Ended										12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues	$ 1,349	$ 978	$ 807	$ 1,320	$ 1,087	[1]	$ 799	[2]	$ 824	$ 1,817	$ 4,454	$ 4,527	$ 6,367
Operating income	108	26	18	166	108	[1]	18	[2]	27	160	318	313	335
Net income (loss)	$ 76	$ 43	$ 6	$ 120	(535)	[1]	(508)	[2]	$ 22	$ 109	$ 245	(912)	$ 323
Enable Midstream Partners [Member]
Impairment Charges					984		862					$ 1,846
Impairment Charge, net of tax					$ 620		$ 537

[1] CERC recognized $984 million ($620 million after tax) in impairment charges related to Enable during the three months ended December 31, 2015.

[2] CERC recognized $862 million ($537 million after tax) in impairment charges related to Enable during the three months ended September 30, 2015.