Deferred Assets and Other Regulatory Assets, Net - Summary of Deferred Assets and Other Regulatory Assets, Net (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Deferred Finance Costs And Other Regulatory Assets Net [Abstract]
Deferred financing costs, Gross Carrying Amount	$ 1,292us-gaap_DeferredFinanceCostsGross	$ 1,290us-gaap_DeferredFinanceCostsGross
Other regulatory assets Deferred financing costs, Gross Carrying Amount	25,748us-gaap_OtherDeferredCostsGross	25,701us-gaap_OtherDeferredCostsGross
Deferred costs recoverable in future years	23,793	23,793
Deferred financing costs and other regulatory assets, Net Gross Carrying Amount	50,833	50,784
Deferred financing costs, Accumulated Amortization	(199)	(143)
Other regulatory assets Deferred financing costs, Accumulated Amortization	(13,549)	(12,693)
Deferred financing costs and other regulatory assets, Net Accumulated Amortization	(13,748)	(12,836)
Deferred financing costs, Net Carrying Amount	1,093us-gaap_DeferredFinanceCostsNet	1,147us-gaap_DeferredFinanceCostsNet
Other regulatory assets Deferred financing costs, Net Carrying Amount	12,199us-gaap_OtherDeferredCostsNet	13,008us-gaap_OtherDeferredCostsNet
Deferred costs recoverable in future years, Net Carrying Amount	23,793	23,793
Deferred financing costs and other regulatory assets, Net Carrying Amount	$ 37,085	$ 37,948

Accumulated amortization of deferred financing costs and other regulatory assets, net cost.

No definition available.

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- Definition

Deferred costs recoverable in future years gross.

+ References

No definition available.

+ Details

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- Definition

Deferred costs recoverable in future years, net.

+ References

No definition available.

+ Details

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- Definition

Deferred finance costs and other regulatory assets net.

+ References

No definition available.

+ Details

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- Definition

Deferred financing costs and other regulatory assets, net gross.

+ References

No definition available.

+ Details

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- Definition

For an unclassified balance sheet, the accumulated amortization, as of the reporting date, representing the periodic charge to earnings of deferred costs which are associated with debt obligations existing as of the end of the period.

+ 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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 17

-Article 5

+ Details

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- Definition

Accumulated amortization of other deferred costs capitalized at the end of the reporting period. Does not include deferred finance costs, deferred acquisition costs of insurance companies, or deferred leasing costs for real estate operations.

+ References

+ Details

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- Definition

For an unclassified balance sheet, the amount as of the balance sheet date of capitalized costs associated with the issuance of debt instruments (for example, legal, accounting, underwriting, printing, and registration costs) that will be charged against earnings over the life of the debt instruments to which such costs pertain. Such amount is before the consideration of accumulated amortization.

+ References

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- Definition

For an unclassified balance sheet, the carrying amount (net of accumulated amortization) as of the balance sheet date of capitalized costs associated with the issuance of debt instruments (for example, legal, accounting, underwriting, printing, and registration costs) that will be charged against earnings over the life of the debt instruments to which such costs pertain.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28555-108399

Reference 2: 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

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 17

-Article 5

+ Details

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- Definition

Gross amount of other deferred costs capitalized at the end of the reporting period. Does not include deferred finance costs or deferred acquisition costs of insurance companies.

+ References

+ Details

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- Definition

Net amount of other deferred costs capitalized at the end of the reporting period. Does not include deferred finance costs or deferred acquisition costs of insurance companies.

+ References

+ Details

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