Earnings Per Share - Computation of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Basic net income per share:
Net income attributable to InfraREIT, Inc.	$ 13,745	$ 12,864
Weighted average common shares outstanding	43,998	43,832
Basic net income per share	$ 0.31	$ 0.29
Diluted net income per share:
Net income attributable to InfraREIT, Inc.	$ 13,745	$ 12,864
Weighted average common shares outstanding	43,998	43,832
Weighted average dilutive shares outstanding	43,998	43,832
Diluted net income per share	$ 0.31	$ 0.29
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	$ 5,224	$ 4,900
Redemption of Operating Partnership units	16,729	16,872