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Deferred Assets and Other Regulatory Assets, Net - Additional Information (Details) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Dec. 10, 2014
Deferred Finance Costs And Other Regulatory Assets Net [Line Items]      
Issuance of aggregate principal amount $ 25,000,000us-gaap_DebtInstrumentFaceAmount    
Deferred costs recoverable in future years 23,793,000hifr_DeferredCostsRecoverableInFutureYearsGross 23,793,000hifr_DeferredCostsRecoverableInFutureYearsGross  
Sharyland Distribution & Transmission Services      
Deferred Finance Costs And Other Regulatory Assets Net [Line Items]      
Credit facility, maximum borrowing capacity 250,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ dei_LegalEntityAxis
= hifr_SharylandDistributionAndTransmissionServicesLimitedLiabilityCompanyMember		    
Revolving Credit Facility | Sharyland Distribution & Transmission Services      
Deferred Finance Costs And Other Regulatory Assets Net [Line Items]      
Credit facility, maximum borrowing capacity     $ 250,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ dei_LegalEntityAxis
= hifr_SharylandDistributionAndTransmissionServicesLimitedLiabilityCompanyMember
Senior Notes      
Deferred Finance Costs And Other Regulatory Assets Net [Line Items]      
Long-term debt, stated interest rate 8.50%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember