Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Lease revenue	$ 55,230	$ 49,419	$ 33,785	$ 33,665	$ 50,921	$ 41,452	$ 29,458	$ 29,372	$ 172,099	$ 151,203	$ 134,415
General and administrative expense	(5,991)	(5,336)	(4,980)	(5,545)	(5,641)	(5,504)	(4,728)	(48,733)	(21,852)	(64,606)	(18,625)
Depreciation	(12,392)	(11,828)	(11,410)	(11,074)	(10,773)	(10,259)	(9,671)	(9,508)	(46,704)	(40,211)	(35,080)
Interest expense, net	(9,644)	(9,379)	(9,055)	(8,842)	(7,470)	(6,723)	(6,939)	(7,422)	(36,920)	(28,554)	(32,741)
Other income	861	1,024	1,137	759	868	707	847	626	3,781	3,048	(17,236)
Income tax expense	(325)	(299)	(293)	(186)	(374)	(243)	(124)	(208)	(1,103)	(949)	(953)
Net income	27,739	23,601	9,184	8,777	27,531	19,430	8,843	(35,873)	69,301	19,931	29,780
Less: Net income attributable to noncontrolling interest	7,749	6,560	2,576	2,462	7,725	5,458	2,481	(9,000)	19,347	6,664	6,882
Net income attributable to InfraREIT, Inc.	$ 19,990	$ 17,041	$ 6,608	$ 6,315	$ 19,806	$ 13,972	$ 6,362	$ (26,873)	$ 49,954	$ 13,267	$ 22,898
Basic EPS	$ 0.46	$ 0.39	$ 0.15	$ 0.14	$ 0.45	$ 0.32	$ 0.15	$ (0.65)	$ 1.14	$ 0.31	$ 0.65
Diluted EPS	$ 0.46	$ 0.39	$ 0.15	$ 0.14	$ 0.45	$ 0.32	$ 0.15	$ (0.65)	$ 1.14	$ 0.31	$ 0.65