Contingent Consideration - Additional Information (Details) - USD ($)			1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Feb. 04, 2015	Jan. 01, 2015	Dec. 31, 2010	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Business Acquisition [Line Items]
Change in fair value of contingent consideration				$ 0	$ 200,000	$ 0	$ 1,110,000
Contingent consideration				$ 0		$ 0		$ 27,378,000
CREZ Project
Business Acquisition [Line Items]
Business combination, contingent consideration, cash payments			$ 737,000,000
Business combination, contingent consideration, fair value			78,600,000
Hunt-InfraREIT
Business Acquisition [Line Items]
Business combination, contingent consideration, capital credits			$ 82,500,000
Hunt-InfraREIT | Operating Partnership Unit
Business Acquisition [Line Items]
Shares issued	983,418
Hunt-InfraREIT | Class A Partnership Units
Business Acquisition [Line Items]
Shares issued		53,246						6,700,000
Hunt-InfraREIT | CREZ Project | Class A Partnership Units
Business Acquisition [Line Items]
Shares issued price per share			$ 10.65