Subsequent Event (Narrative) (Details) - USD ($)
$ / shares in Units, $ in Millions |
|
9 Months Ended |
|
Nov. 01, 2016 |
Sep. 30, 2016 |
Dec. 31, 2015 |
| Subsequent Event [Line Items] |
|
|
|
| Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest Additional Ownership Interest |
|
46.50%
|
|
| Subsequent Event |
|
|
|
| Subsequent Event [Line Items] |
|
|
|
| Distribution Made to Limited Partner, Distributions Declared, Per Unit |
$ 0.1975
|
|
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| Distribution Made to Limited Partner, Distribution Date |
Nov. 18, 2016
|
|
|
| Distribution Made to Limited Partner, Date of Record |
Nov. 11, 2016
|
|
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| Business Acquisition, Date of Acquisition Agreement |
Nov. 01, 2016
|
|
|
| Business Acquisition, Unit Price |
$ 17.00
|
|
|
| Daily Distribution Rate |
0.00217
|
|
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| Distribution to Limited Partner, Minimum Quarterly Distribution, Per Unit |
$ 0.1975
|
|
|
| Number of days in quarter |
91
|
|
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| Subordinated Units |
|
|
|
| Subsequent Event [Line Items] |
|
|
|
| Limited Partners' Capital Account, Units Outstanding |
|
46,811,398
|
46,811,398
|
| Subordinated Units | Columbia Energy Group |
|
|
|
| Subsequent Event [Line Items] |
|
|
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| Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest |
|
100.00%
|
|
| Limited Partners' Capital Account, Units Outstanding |
|
46,811,398
|
|
| Columbia Pipeline Group |
|
|
|
| Subsequent Event [Line Items] |
|
|
|
| Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest |
|
100.00%
|
|
| Columbia Energy Group | Subordinated Units |
|
|
|
| Subsequent Event [Line Items] |
|
|
|
| Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest Additional Ownership Interest |
|
46.50%
|
|
| Maximum [Member] | Subsequent Event |
|
|
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| Subsequent Event [Line Items] |
|
|
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| Termination Payment |
$ 10.0
|
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