Financial Information by Business Segment - Schedule of Segment Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Segment assets:
Total assets	$ 14,889,984	$ 13,976,172
Operating Segments
Segment assets:
Total assets	12,975,991	12,221,991
Operating Segments | EQT Production
Segment assets:
Total assets	9,222,067	8,995,853
Operating Segments | EQT Midstream
Segment assets:
Total assets	3,753,924	3,226,138
Headquarters assets, including cash and short-term investments
Segment assets:
Total assets	$ 1,913,993	$ 1,754,181