Financial Information by Business Segment (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating segments information
Third-party transportation costs									$ 126,783,000	$ 87,034,000	$ 51,687,000
Revenues from external customers	489,787,000	364,057,000	337,804,000	449,960,000	436,804,000	362,644,000	367,791,000	472,695,000	1,641,608,000	1,639,934,000	1,374,395,000
Operating income	150,990,000	85,948,000	81,404,000	152,186,000	172,753,000	314,984,000	153,170,000	220,412,000	470,528,000	861,319,000	470,479,000
Gains (Losses) on dispositions										202,928,000
Reconciliation of operating income to net income:
Other income									15,965,000	34,138,000	12,898,000
Interest expense									184,786,000	136,328,000	128,157,000
Income taxes									105,296,000	279,360,000	127,520,000
Net income									196,411,000	479,769,000	227,700,000
Depreciation, depletion, and amortization									499,118,000	339,297,000	270,285,000
Expenditure for segment assets									1,399,385,000	1,366,894,000	1,477,619,000
Expenditure on segment assets for the acquisition of producing properties										92,600,000
Equitable Gas and Homeworks
Operating segments information
Expenses related to the pending sale of properties									4,500,000
EQT Production
Operating segments information
Revenues from external customers									793,773,000	791,285,000	537,657,000
Operating income									187,913,000	387,098,000	223,487,000
Reconciliation of operating income to net income:
Depreciation, depletion, and amortization									409,628,000	257,144,000	183,699,000
Expenditure for segment assets									991,775,000	1,087,840,000	1,245,914,000
Expenditures for segment assets for undeveloped property acquisitions									134,600,000	57,200,000	357,700,000
Expenditure on segment assets for the acquisition of producing properties										92,600,000
Undeveloped property acquisition amount											230,700,000
EQT Midstream
Operating segments information
Revenues from external customers									505,498,000	525,345,000	580,698,000
Operating income									237,324,000	416,611,000	178,866,000
Gains (Losses) on dispositions										202,900,000
Reconciliation of operating income to net income:
Depreciation, depletion, and amortization									64,782,000	57,135,000	61,863,000
Expenditure for segment assets									375,731,000	242,886,000	193,128,000
Distribution
Operating segments information
Revenues from external customers									313,990,000	419,678,000	474,143,000
Operating income									68,614,000	86,898,000	83,182,000
Reconciliation of operating income to net income:
Depreciation, depletion, and amortization									24,454,000	25,747,000	24,174,000
Expenditure for segment assets									28,745,000	31,313,000	36,619,000
Other
Reconciliation of operating income to net income:
Depreciation, depletion, and amortization									254,000	(729,000)	549,000
Expenditure for segment assets									3,134,000	4,855,000	1,958,000
Less intersegment revenues, net
Operating segments information
Revenues from external customers									(98,436,000)	(183,408,000)	(269,790,000)
Unallocated expenses
Operating segments information
Operating income									(23,323,000)	(29,288,000)	(15,056,000)
Unallocated expenses | Equitable Gas and Homeworks
Operating segments information
Expenses related to the pending sale of properties									$ 4,500,000