Basis of Accounting Presentation Basis of Accounting Presentation (Details) - 6 months ended Jun. 30, 2015 |
Total |
|---|---|
| Basis Of Accounting Presentation [Line Items] | |
| Number Of Customers | 3,800,000 |
| Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest | 15.70% |
| Limited Liability Company or Limited Partnership, Managing Member or General Partner, Name | CPP GP LLC |
| Corporate Joint Venture [Member] | |
| Basis Of Accounting Presentation [Line Items] | |
| Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest | 84.30% |