| **Summary of Significant Accounting Policies (Details 2) - USD ($) $ in Millions** | Dec. 31, 2015 | Apr. 28, 2015 | Dec. 31, 2014 |
|------------------------------------------------------------------------------------|---------------|---------------|---------------|
| **Change in Stockholder Equity Due to Shareholder Amendment [Line Items]**         |          |          |          |
| Common Stock, shares authorized (in shares)                                        | 1,000,000,000 |          | 500,000,000   |
| Unamortized Debt Issuance Expense                                                  | $ 12          |          | $ 15          |
| Common Stock Authorized prior to Certificate of Incorporation Amendment            |          |          |          |
| **Change in Stockholder Equity Due to Shareholder Amendment [Line Items]**         |          |          |          |
| Common Stock, shares authorized (in shares)                                        | 500,000,000   |          |          |
| Common Stock Authorized after Certificate of Incorporation Amendment               |          |          |          |
| **Change in Stockholder Equity Due to Shareholder Amendment [Line Items]**         |          |          |          |
| Common Stock, shares authorized (in shares)                                        |          | 1,000,000,000 |          |

| X                                                                                                                                                                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
[Line Items] for Change in Stockholder Equity Due to Shareholder Amendment [Table]
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
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| - Definition
The maximum number of common shares permitted to be issued by an entity's charter and bylaws.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.29) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 30 -Article 5
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682
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| X                                                                                                                                                                                                       |
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| X                                                                                                                                                                                                     |
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