Fair Value (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Financial Instruments [Abstract]
Total debt, excluding total other financing obligations, Carrying Amount	$ 475	[1]	$ 475	[1]
Total debt, excluding total other financing obligations, Fair Value	$ 534	[1]	$ 561	[1]

[1] Our other financing obligations were $170 million and $172 million as of September 30, 2013 and December 31, 2012, of which $5 million was reported as "Current portion of debt" on our Consolidated Balance Sheets for each period. For a further discussion of our other financing obligations, see our 2012 Form 10-K.