Financial Information by Business Segment - Schedule of Segment Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Operating segments information
Total assets	$ 13,572,330	$ 12,064,900
Operating segments
Operating segments information
Total assets	11,527,152	10,862,251
Operating segments | EQT Production
Operating segments information
Total assets	8,538,111	8,153,199
Operating segments | EQT Midstream
Operating segments information
Total assets	2,989,041	2,709,052
Headquarters assets, including cash and short-term investments
Operating segments information
Total assets	$ 2,045,178	$ 1,202,649