| **Fair Value Measurements and Disclosures (Details 3) (USD $)In Millions, unless otherwise specified**                                                                  | Dec. 31, 2014                                                                                                                          | Dec. 31, 2013 |
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| Estimate of Fair Value Measurement [Member]                                                                                                                             |                                                                                                                                   |               |   |  |
| **Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]**                                                                                       |                                                                                                                                   |               |   |  |
| Long-term Debt, Net of Unamortized Discount                                                                                                                             | $ 6,179us-gaap_LongTermDebtFairValue/ us-gaap_FairValueByMeasurementBasisAxis= us-gaap_EstimateOfFairValueFairValueDisclosureMember    | [1]           | $ 4,959us-gaap_LongTermDebtFairValue/ us-gaap_FairValueByMeasurementBasisAxis= us-gaap_EstimateOfFairValueFairValueDisclosureMember | [1] |
| Reported Value Measurement [Member]                                                                                                                                     |                                                                                                                                   |               |   |  |
| **Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]**                                                                                       |                                                                                                                                   |               |   |  |
| Long-term Debt, Net of Unamortized Discount                                                                                                                             | $ 5,758us-gaap_LongTermDebtFairValue/ us-gaap_FairValueByMeasurementBasisAxis= us-gaap_CarryingReportedAmountFairValueDisclosureMember | [1]           | $ 4,465us-gaap_LongTermDebtFairValue/ us-gaap_FairValueByMeasurementBasisAxis= us-gaap_CarryingReportedAmountFairValueDisclosureMember | [1] |
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| [1]Excludes capital lease and other obligations. No floating rate debt was outstanding at December 31, 2014 or December 31, 2013. See Note 9. Long-Term Debt. |

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| - Definition
The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.
+ References
No definition available.
+ Details**Name:**us-gaap_LongTermDebtFairValue**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
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