Investments in Affiliates Transactions with Affiliates (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Equity Method Investments and Joint Ventures [Abstract] | |||
| Sales to affiliates | $ 42 | $ 57 | $ 47 |
| Purchases from affiliates | $ 48 | $ 55 | $ 54 |