Other Assets and Liabilities - Other Current Assets (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Other Assets, Current [Abstract]
Other receivables	$ 36	$ 36
Prepaid expenses	22	29
Certificates of deposit	27	27
Other current assets	2	3
Total other current assets	$ 87	$ 95