EQT Midstream Partners, LP (Details) - EQM - Subsequent Event - USD ($) $ / shares in Units, $ in Millions	Jul. 27, 2017	Jul. 25, 2017
Subsidiary or equity method investee
Distribution made to limited partner and general partner, cash distributions declared	$ 56.5
Cash distribution declared	20.4
Distribution made to general partner, cash distributions declared	1.9
Cash distribution declared related to IDRs	$ 34.2
General Partner
Subsidiary or equity method investee
Cash distribution declared (in dollars per share)		$ 0.935
Common unit, outstanding (in shares)	80,581,758