Investments in Affiliates Transactions with Affiliates (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Equity Method Investments and Joint Ventures [Abstract]
Sales to affiliates	$ 32	$ 42	$ 57
Purchases from affiliates	$ 36	$ 48	$ 55