Variable Interest Entities - Schedule of Sale and Deconsolidation of a Variable Interest Entity (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended		1 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	May 31, 2014 CCH [Member]
Variable Interest Entity [Line Items]
Proceeds from sale, net of transaction costs of $1	$ 108		$ 108
Non-utility property, less accumulated depreciation	(349)	(605)	(341)
Other assets, including working capital			(31)
Long-term debt, including current portion	11,195	10,974	217
Other liabilities			9
Gain on sale of solar energy projects	(45)		(45)
Equity method investment upon deconsolidation			$ (83)