Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income Loss [Line Items]
Other comprehensive (loss) income before reclassifications	$ (49)	$ (236)
Amounts reclassified from accumulated other comprehensive (loss) income	893	1,559
Net period other comprehensive income	844	1,323
Accumulated Other Comprehensive Loss Attributable to InfraREIT, Inc.
Accumulated Other Comprehensive Income Loss [Line Items]
Other comprehensive (loss) income before reclassifications	(77)	(180)
Amounts reclassified from accumulated other comprehensive (loss) income	687	1,180
Net period other comprehensive income	610	1,000
Accumulated Other Comprehensive Loss Attributable To Noncontrolling Interest
Accumulated Other Comprehensive Income Loss [Line Items]
Other comprehensive (loss) income before reclassifications	28	(56)
Amounts reclassified from accumulated other comprehensive (loss) income	206	379
Net period other comprehensive income	$ 234	$ 323