Non-wholly Owned Entities - Income from Equity Method Investments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	$ 6	$ 8	$ 3
Triton [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	4	6	9
Horizon Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	2	2	2
Other [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	$ 0	$ 0	$ (8)