Investment in Unconsolidated Affiliates Summarized Income Statement of Equity Method Investment (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Summarized Income Statement of Equity Method Investment [Abstract]
Operating revenues	$ 803	$ 796	$ 2,632	$ 1,298
Cost of sales	439	458	1,550	753
Operating income	152	132	452	207
Net income attributable to Enable	$ 139	$ 123	$ 408	$ 188