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Rates and Other Regulatory Activities - Additional Information (Detail) |  |  |  | 1 Months Ended | 3 Months Ended
--- | --- | --- | --- | --- | ---
Feb. 19, 2016 USD ($) | Dec. 21, 2015 USD ($) | Oct. 13, 2015 dekatherm / d | Dec. 31, 2015 USD ($) | Mar. 31, 2016 dekatherm / d in mi
Rates and Other Regulatory Activities [Line Items] |  |  |  |  |
Public Utilities, Interim Rate Increase (Decrease), Amount | $ | $ 2,500,000 |  |  |  |
Public Utilities Interim Requested Rate Increase (Decrease) Percentage | 5.00% |  |  |  |
DELAWARE |  |  |  |  |
Rates and Other Regulatory Activities [Line Items] |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount | $ |  | $ 4,700,000 |  |  |
Public Utilities, Requested Rate Increase (Decrease), Percentage |  | 10.00% |  |  |
MARYLAND |  |  |  |  |
Rates and Other Regulatory Activities [Line Items] |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount | $ |  |  |  | $ 950,000 |
Public Utilities, Requested Rate Increase (Decrease), Percentage |  |  |  | 5.00% |
Eastern Shore [Member] |  |  |  |  |
Rates and Other Regulatory Activities [Line Items] |  |  |  |  |
Volume The Expansion Project Is Expected to Provide | dekatherm / d |  |  | 53,000 |  |
Total Capacity After Pipeline Improvements | dekatherm / d |  |  | 160,000 |  |
White Oak Lateral Mainline Expansion [Member] | Eastern Shore [Member] |  |  |  |  |
Rates and Other Regulatory Activities [Line Items] |  |  |  |  |
Volume The Expansion Project Is Expected to Provide | dekatherm / d |  |  |  |  | 45,000
Number of pipeline miles | mi |  |  |  |  | 7.2
Lateral diamater of pipeline to be installed | in |  |  |  |  | 16
Horsepower Of Additional Compression |  |  |  |  | 3,550
System Reliability Project [Member] | Eastern Shore [Member] |  |  |  |  |
Rates and Other Regulatory Activities [Line Items] |  |  |  |  |
Number of pipeline miles | mi |  |  |  |  | 10.1
Lateral diamater of pipeline to be installed | in |  |  |  |  | 16

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- Definition Volume The Expansion Project Is Expected to Provide + References No definition available. + Details
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- Definition Amount of public utility's interim rate increase (decrease) allowed while waiting final decision of regulatory agency. + References No definition available. + Details
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