Regulatory Matters (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Schedule of regulatory assets and liabilities [Abstract]
Current regulatory assets	$ 8		$ 6
Non-current regulatory assets	12	[1]	14	[1]
Total Regulatory Assets	20		20
Current regulatory liabilities	3		9
Non-current regulatory liabilities	10	[2]	10	[2]
Total Regulatory Liabilities	$ 13		$ 19

[1] Included in "Deferred charges and other assets" on our accompanying Consolidated Balance Sheets.

[2] Included in "Other long-term liabilities and deferred credits" on our accompanying Consolidated Balance Sheets.