Financial Information by Business Segment - Schedule of Segment Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Segment assets:
Total assets	$ 27,632,346	$ 29,522,604
Operating Segments
Segment assets:
Total assets	26,463,679	28,491,976
Operating Segments | EQT Production
Segment assets:
Total assets	20,633,392	22,711,854
Operating Segments | EQM Gathering
Segment assets:
Total assets	1,449,871	1,411,857
Operating Segments | EQM Transmission
Segment assets:
Total assets	1,475,214	1,462,881
Operating Segments | RMP Gathering
Segment assets:
Total assets	2,741,744	2,720,305
Operating Segments | RMP Water
Segment assets:
Total assets	163,458	185,079
Headquarters assets, including cash and short-term investments
Segment assets:
Total assets	$ 1,168,667	$ 1,030,628