Debt (First Lien Notes) (Details) - USD ($) $ in Millions |
Jun. 30, 2016 |
May 31, 2016 |
Dec. 31, 2015 |
|---|---|---|---|
| Debt Instrument [Line Items] | |||
| Long-term Debt | $ 11,682 | $ 11,292 | |
| 2022 First Lien Notes [Member] | |||
| Debt Instrument [Line Items] | |||
| Long-term Debt | 738 | 737 | |
| First Lien Notes 2023 [Member] | |||
| Debt Instrument [Line Items] | |||
| Long-term Debt | 569 | 568 | |
| 2024 First Lien Notes [Member] | |||
| Debt Instrument [Line Items] | |||
| Long-term Debt | 484 | 484 | |
| 2026 First Lien Notes [Member] | |||
| Debt Instrument [Line Items] | |||
| Debt Instrument, Face Amount | $ 625 | ||
| Long-term Debt | 616 | 0 | |
| Debt Instrument, Interest Rate, Stated Percentage | 5.25% | ||
| Debt Issuance Costs, Net | $ 9 | ||
| Corporate Debt Securities [Member] | |||
| Debt Instrument [Line Items] | |||
| Long-term Debt | $ 2,407 | $ 1,789 |