Non-Wholly Owned Entities (Details) - Income from Equity Method Investments - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Triton [Member]
Schedule of Equity Method Investments [Line Items]
Income from equity method investment	$ 2	$ 2	$ 3	$ 5
Horizon Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Income from equity method investment	$ 0	$ 0	$ 1	$ 1