Fair Value Measurements - Assets and Liabilities Measured on a Recurring Basis (Details) (Recurring Basis [Member], USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Assets:
Cash equivalents	$ 118	$ 27
Restricted cash	4	2
Interest rate swaps	8	14
Total assets	130	43
Liabilities:
Interest rate swaps	5	0
Total liabilities	5	0
Level 1 [Member]
Assets:
Cash equivalents	118	27
Restricted cash	4	2
Interest rate swaps	0	0
Total assets	122	29
Liabilities:
Interest rate swaps	0	0
Total liabilities	0	0
Level 2 [Member]
Assets:
Cash equivalents	0	0
Restricted cash	0	0
Interest rate swaps	8	14
Total assets	8	14
Liabilities:
Interest rate swaps	5	0
Total liabilities	$ 5	$ 0