Summary of Significant Accounting Policies - Schedule of Regulated Net Revenues and Operating Expenses (Details) - EQT Transmission and Storage - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Net revenues	$ 390,883	$ 347,320	$ 309,984
Operating expenses	$ 151,510	$ 118,611	$ 109,954