Debt Senior Unsecured Notes (Details) - USD ($) |
3 Months Ended | 12 Months Ended | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2016 |
Mar. 31, 2015 |
Sep. 30, 2014 |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
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| Debt Instrument [Line Items] | |||||||||||||||
| Long-term Debt | $ 12,046,000,000 | $ 12,046,000,000 | $ 11,292,000,000 | ||||||||||||
| Debt Issuance Costs, Net | 154,000,000 | 154,000,000 | |||||||||||||
| Gains (Losses) on Extinguishment of Debt | (25,000,000) | (40,000,000) | $ (346,000,000) | ||||||||||||
| Senior Unsecured Notes 2023 [Member] | |||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||
| Long-term Debt | $ 1,237,000,000 | $ 1,237,000,000 | $ 1,235,000,000 | ||||||||||||
| Debt Instrument, Interest Rate, Effective Percentage | [1] | 5.50% | 5.50% | 5.60% | |||||||||||
| Debt Instrument, Face Amount | $ 1,250,000,000 | ||||||||||||||
| Debt Instrument, Interest Rate, Stated Percentage | 5.375% | ||||||||||||||
| Senior Unsecured Notes 2024 [Member] | |||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||
| Long-term Debt | $ 643,000,000 | $ 643,000,000 | $ 641,000,000 | ||||||||||||
| Debt Instrument, Interest Rate, Effective Percentage | [1] | 5.60% | 5.60% | 5.70% | |||||||||||
| Debt Instrument, Face Amount | $ 650,000,000 | ||||||||||||||
| Debt Instrument, Interest Rate, Stated Percentage | 5.50% | ||||||||||||||
| Debt Issuance Costs, Net | $ 9,000,000 | ||||||||||||||
| Senior Unsecured Notes 2025 [Member] | |||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||
| Long-term Debt | $ 1,532,000,000 | $ 1,532,000,000 | $ 1,530,000,000 | ||||||||||||
| Debt Instrument, Interest Rate, Effective Percentage | [1] | 5.90% | 5.90% | 6.00% | |||||||||||
| Debt Instrument, Face Amount | $ 1,550,000,000 | ||||||||||||||
| Debt Instrument, Interest Rate, Stated Percentage | 5.75% | ||||||||||||||
| Unsecured Debt [Member] | |||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||
| Long-term Debt | $ 3,412,000,000 | $ 3,412,000,000 | $ 3,406,000,000 | ||||||||||||
| First Lien Notes 2023 [Member] | |||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||
| Long-term Debt | [2],[3] | $ 450,000,000 | $ 450,000,000 | $ 568,000,000 | |||||||||||
| Debt Instrument, Interest Rate, Effective Percentage | [4] | 8.10% | 8.10% | 8.10% | |||||||||||
| Gains (Losses) on Extinguishment of Debt | $ (5,000,000) | (19,000,000) | |||||||||||||
| First Lien Notes 2023 [Member] | Early Redemption Amount [Member] | |||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||
| Long-term Debt | $ 147,000,000 | ||||||||||||||
| 2019, 2020 and 2021 First Lien Notes [Member] | |||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||
| Gains (Losses) on Extinguishment of Debt | $ (340,000,000) | ||||||||||||||
| 2023 and 2025 Senior Unsecured Notes [Member] | |||||||||||||||
| Debt Instrument [Line Items] | |||||||||||||||
| Debt Issuance Costs, Net | $ 42,000,000 | ||||||||||||||
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