Discontinued Operations (Details) (USD $)	3 Months Ended								12 Months Ended			0 Months Ended	12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 17, 2013 Equitable Gas and Homeworks	Dec. 31, 2013 Equitable Gas and Homeworks	Dec. 31, 2012 Equitable Gas and Homeworks	Dec. 31, 2013 Equitable Gas and Homeworks EQT Midstream	Dec. 31, 2012 Equitable Gas and Homeworks EQT Midstream	Dec. 31, 2011 Equitable Gas and Homeworks EQT Midstream
Discontinued operations
Percentage of ownership interests of Equitable Gas Company, LLC (Equitable Gas) and Equitable Homeworks, LLC (Homeworks) to PNG Companies												100.00%
Cash payment received												$ 740,600,000
Preliminary estimated fair value of consideration received												141,400,000
Preliminary estimated fair value of other contractual assets received as consideration												32,500,000
Lease rent receivable per year												2,500,000
Period for which lease rent will be received												20 years
Lease receivable, net of unearned interest													19,700,000
Intangible assets resulted from other contractual agreements acquired												12,800,000
Value of energy marketing contracts												5,000,000
Amortization period of remaining contract-based intangible												5 years
Gain on sale of business												43,800,000
Income from discontinued operations, net of tax												122,500,000
Equitable Gas transaction costs													8,100,000	4,500,000
Write off of income tax related regulatory assets													51,600,000
Period of long-term commercial arrangements with PNG Companies and its affiliates													20 years
Intra-entity revenues															37,600,000	36,800,000	37,900,000
Summary of the discontinued operations activity
Operating revenues									332,947,000	314,821,000	420,563,000
Income from discontinued operations before income taxes									251,378,000	81,328,000	101,010,000
Income taxes									159,535,000	33,835,000	40,823,000
Income from discontinued operations, net of tax	53,272,000	2,057,000	5,390,000	31,124,000	14,918,000	2,863,000	6,144,000	23,568,000	91,843,000	47,493,000	60,187,000
Assets
Accounts receivable and unbilled receivables					42,919,000					42,919,000
Inventory					31,622,000					31,622,000
Other current assets					18,137,000					18,137,000
Total current assets					92,678,000					92,678,000
Property, plant and equipment, net					655,886,000					655,886,000
Regulatory assets					93,599,000					93,599,000
Other assets					571,000					571,000
Total noncurrent assets					750,056,000					750,056,000
Assets of discontinued operations					842,734,000					842,734,000
Liabilities
Accounts payable					12,230,000					12,230,000
Accrued customer credits					32,376,000					32,376,000
Other current liabilities					3,685,000					3,685,000
Total current liabilities					48,291,000					48,291,000
Deferred income taxes					223,959,000					223,959,000
Pension and other post-retirement benefits					27,985,000					27,985,000
Other liabilities					5,671,000					5,671,000
Total noncurrent liabilities					257,615,000					257,615,000
Liabilities of discontinued operations					$ 305,906,000					$ 305,906,000