Description of Business and Presentation of Financial Statements - Additional Information (Details) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended	9 Months Ended
	Mar. 09, 2015 shares	Feb. 04, 2015 USD ($) Director $ / shares shares	Feb. 28, 2015 USD ($)	Mar. 31, 2015 USD ($)	Sep. 30, 2015 USD ($) shares	Jan. 29, 2015 shares	Dec. 31, 2014 USD ($) shares
Description Of Business And Presentation Of Financial Statements [Line Items]
Business combination, assets assumed, marketable securities | $					$ 1,100
Business combination, liabilities assumed, notes payable | $					1,000
Proceeds from sale of marketable securities | $					1,065
Realized gain on sale of marketable securities | $					$ 66
Percentage of partnership units outstanding					71.90%
Common stock, shares issued under IPO					43,565,495
Net proceeds from issuance of common stock upon initial public offering | $		$ 172,400			$ 493,722
Contributed to the operating partnership | $		$ 323,200
Offering expenses | $					6,300		$ 4,397
Non-cash expense | $					44,897
Number of directors | Director		7
Members capital, shares issued							35,053,186
Westwood Trust
Description Of Business And Presentation Of Financial Statements [Line Items]
Shares purchased consideration for promissory note		6,242,999
Principal amount of shares purchased consideration for promissory note | $		$ 66,500
Common Class A
Description Of Business And Presentation Of Financial Statements [Line Items]
Common shares received		19,617,755
Common Class C
Description Of Business And Presentation Of Financial Statements [Line Items]
Common shares received		25,145
LTIP Units
Description Of Business And Presentation Of Financial Statements [Line Items]
Operating partnership issued		28,000
Revolving Credit Facility
Description Of Business And Presentation Of Financial Statements [Line Items]
Repayments of outstanding revolving credit facility | $					72,000
Sharyland Distribution & Transmission Services | Revolving Credit Facility
Description Of Business And Presentation Of Financial Statements [Line Items]
Repayments of outstanding revolving credit facility | $					$ 150,000
InfraREIT, L.L.C.
Description Of Business And Presentation Of Financial Statements [Line Items]
Common stock, shares issued under IPO		1,700,000
Common stock sold under IPO, per share | $ / shares		$ 21.551
Contributed to the operating partnership | $		$ 323,200
Partners capital received		8,000,000
Members capital, shares issued		15,000,000
Common stock conversion basis					one-for-one basis
InfraREIT, L.L.C. | Common Class A
Description Of Business And Presentation Of Financial Statements [Line Items]
Common shares received		19,617,755
InfraREIT, L.L.C. | Common Class C
Description Of Business And Presentation Of Financial Statements [Line Items]
Common shares received		25,145
InfraREIT, L.L.C. | LTIP Units
Description Of Business And Presentation Of Financial Statements [Line Items]
Common shares received	11,264
Common stock conversion basis					one-to-one basis
InfraREIT, L.L.C. | Operating Partnership Unit
Description Of Business And Presentation Of Financial Statements [Line Items]
Reverse share split						0.938550
Hunt-InfraREIT
Description Of Business And Presentation Of Financial Statements [Line Items]
Common stock, shares issued under IPO		1,551,878				1,700,000
Non-cash expense | $				$ 44,900
Operating partnership issued		1,167,287
Common shares received	2,329,283
Hunt-InfraREIT | CREZ Project
Description Of Business And Presentation Of Financial Statements [Line Items]
Operating partnership issued		983,814
Hunt-InfraREIT | Operating Partnership Unit
Description Of Business And Presentation Of Financial Statements [Line Items]
Common shares received		1,551,878
MC Transmission Holdings Inc. | Operating Partnership Unit
Description Of Business And Presentation Of Financial Statements [Line Items]
Shares purchased consideration for promissory note		3,325,874
Initial Public Offering
Description Of Business And Presentation Of Financial Statements [Line Items]
Common stock, shares issued under IPO		23,000,000
Common stock sold under IPO, per share | $ / shares		$ 23.00
Net proceeds from issuance of common stock upon initial public offering | $		$ 529,000
Offering expenses | $							$ 4,400
Hunt Consolidated Incorporation
Description Of Business And Presentation Of Financial Statements [Line Items]
Percentage of partnership units outstanding					28.10%
Repayments of related party debt | $			$ 1,000		$ 1,000