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Duration of Firm Capacity Commitments

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Firms Capacity Commitments Per Day

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Gas and Oil, Length of Natural Gas Pipeline

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Represents the amount of average daily balance outstanding under credit facility.

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Partners' Capital Account, Percent, Contributed

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Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Percentage of voting equity interests acquired at the acquisition date in the business combination.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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No definition available.

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Weighted average interest rate of debt outstanding.

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Amount of equity impact of cash distributions declared to unit-holder of limited liability company (LLC).

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Per unit of ownership amount of cash distributions declared to unit-holder of a limited liability company (LLC).

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Amount of equity impact of cash distribution declared to unit-holder of limited partnership (LP).

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Percentage investment held by members or limited partners of limited liability company (LLC) or limited partnership (LP).

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Maximum amount borrowed under the credit facility at any time during the period.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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The cash inflow from a borrowing with the highest claim on the assets of the entity in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle, if longer).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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EQT Midstream Partners, LP - Additional Information (Details)								1 Months Ended	3 Months Ended	12 Months Ended
	Feb. 02, 2018 USD ($)	Jan. 18, 2018 USD ($) $ / shares	Oct. 26, 2016 USD ($)	Oct. 13, 2016 USD ($)	Apr. 15, 2015 USD ($)	Mar. 30, 2015 USD ($)	Mar. 17, 2015 USD ($)	Nov. 30, 2016 USD ($)	Dec. 31, 2017 USD ($) mi	Dec. 31, 2017 USD ($) Bcf / d mi	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Feb. 15, 2018	Nov. 13, 2017 USD ($)	Jul. 31, 2017 USD ($)	Jan. 21, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Asset impairment charges										$ 0		$ 4,200,000
Principal value									$ 5,618,200,000	$ 5,618,200,000	$ 3,318,200,000
Cash distribution declared in respect of limited partner and general partner interest									8,400,000
Revolving Credit Facility
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum borrowing capacity														$ 2,500,000,000.0
Long-term line of credit												$ 0
Unallocated Expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Asset impairment charges											59,700,000
NWV Gathering
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total consideration							$ 925,700,000
EQT Energy Supply, LLC
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total consideration					$ 124,300,000
MVP Holdco
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of membership interest						100.00%
MVP Joint Venture
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total consideration						$ 54,200,000
Percentage of capital contributions						100.00%
Firms capacity commitments per day (in Bcf per day) \| Bcf / d										2.0
Duration of firm capacity commitments (in years)										20 years
Allegheny Valley Connector LLC and Rager Mountain Storage Company LLC
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total consideration				$ 275,000,000
Ownership interest (as a percent)				100.00%
EQM
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum borrowing capacity									1,000,000,000	$ 1,000,000,000					$ 1,000,000,000.0
EQM \| Line of credit \| Revolving Credit Facility
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum borrowing capacity			$ 500,000,000
Debt instrument, term (in days)			364 days
Non-renewal notice (in days)			60 days
Basis spread on variable rate			0.10%
Long-term line of credit									$ 0	0
Maximum amount of outstanding borrowings										100,000,000	$ 0
Average daily amount outstanding										$ 23,000,000
Weighted average interest rate									2.20%	2.20%
EQM \| Senior Notes \| 4.125% EQM Notes, due December 1, 2026
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Interest rate								4.125%
Principal value								$ 500,000,000
Proceeds from issuance of senior notes								$ 491,400,000
EQM \| Variable Interest Entity, Not Primary Beneficiary \| MVP Joint Venture
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ownership percentage									45.50%	45.50%
EQM \| Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash distribution declared (in dollars per share) \| $ / shares		$ 1.025
EQM \| Subsequent Event \| Variable Interest Entity, Not Primary Beneficiary \| MVP Joint Venture
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ownership percentage													45.50%
EQM \| MVP Joint Venture \| Variable Interest Entity, Not Primary Beneficiary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ownership percentage																45.50%
EQT \| MVP Joint Venture
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Firms capacity commitments per day (in Bcf per day) \| Bcf / d										1.29
EQGP \| Scenario, Forecast
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash distribution declared	$ 65,700,000
EQGP \| Scenario, Forecast \| Limited Partner
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash distribution declared in respect of limited partner and general partner interest	22,400,000
EQGP \| Scenario, Forecast \| General Partner
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash distribution declared in respect of limited partner and general partner interest	2,200,000
Incentive distribution rights declared	$ 41,100,000
EQGP \| Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash distribution declared in respect of limited partner and general partner interest		$ 64,900,000
Mountain Valley Pipeline
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Natural gas interstate pipeline (in miles) \| mi									300	300