Income Taxes Income Taxes (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Tax Contingency [Line Items]
Effective tax rate			6.90%	33.30%
Effective tax rate, excluding impact of recently received IRS guidance			15.50%
Income tax benefit	$ (35,936,000)	$ (64,496,000)	$ (28,393,000)	$ (239,920,000)
Deferred Income Tax Charge
Income Tax Contingency [Line Items]
Amortization period for regulatory asset			32 years
Equitable Gas Company, LLC
Income Tax Contingency [Line Items]
Income tax benefit			$ 35,500,000
EQT Midstream Partners LP
Income Tax Contingency [Line Items]
Common unit aggregate offering price, maximum amount (in dollars per share)	$ 750,000,000