Earnings Per Share - Computation of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Basic net income per share:
Net income (loss) attributable to InfraREIT, Inc.	$ 13,972	$ 11,894	$ (6,539)	$ 19,974
Weighted average common shares outstanding	43,565	35,053	42,787	35,053
Basic net income (loss) per share	$ 0.32	$ 0.34	$ (0.15)	$ 0.57
Diluted net income per share:
Net income (loss) attributable to InfraREIT, Inc.	$ 13,972	$ 11,894	$ (6,539)	$ 19,974
Weighted average common shares outstanding	43,565	35,053	42,787	35,053
Weighted average dilutive shares outstanding	43,565	35,053	42,787	35,053
Diluted net income (loss) per share	$ 0.32	$ 0.34	$ (0.15)	$ 0.57
Due to the anti-dilutive effect, the computation of diluted earnings per share does not reflect the following adjustments:
Net income (loss) attributable to noncontrolling interest	$ 5,458	$ 3,621	$ (1,061)	$ 6,046
Redemption of operating partnership units	17,028	10,656	15,964	10,546