Earnings Per Share - Computation of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Basic net income per share:
Net income attributable to InfraREIT, Inc.	$ 7,949	$ 6,315
Weighted average common shares outstanding	43,775	43,570
Basic net income per share	$ 0.18	$ 0.14
Diluted net income per share:
Net income attributable to InfraREIT, Inc.	$ 7,949	$ 6,315
Weighted average common shares outstanding	43,775	43,570
Weighted average dilutive shares outstanding	43,775	43,570
Diluted net income per share	$ 0.18	$ 0.14
Due to the anti-dilutive effect, the computation of diluted earnings per share does not reflect the following adjustments:
Net income attributable to noncontrolling interest	$ 3,068	$ 2,462
Redemption of Operating Partnership units	16,900	17,057