Debt Debt (Repayment Amounts) (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended |
|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2016 |
|
| Debt Instrument [Line Items] | ||
| Aggregate Principal | $ 115 | $ 208 |
| Cash Payment | 109 | 195 |
| Term loans [Member] | ||
| Debt Instrument [Line Items] | ||
| Aggregate Principal | 0 | 50 |
| Cash Payment | 0 | 49 |
| 2023 Notes [Member] | ||
| Debt Instrument [Line Items] | ||
| Aggregate Principal | 73 | 116 |
| Cash Payment | 70 | 107 |
| Euro Notes [Member] | ||
| Debt Instrument [Line Items] | ||
| Aggregate Principal | 42 | 42 |
| Cash Payment | $ 39 | $ 39 |