Dominion Energy Midstream Partners 10-Q 9 Nov 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Oct. 15, 2016
Document and Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Trading Symbol	DM
Entity Registrant Name	Dominion Midstream Partners, LP
Entity Central Index Key	1,603,286
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Units Outstanding
Document and Entity Information [Line Items]
Entity Units Outstanding		45,722,371
Entity Subordinated Units Outstanding
Document and Entity Information [Line Items]
Entity Units Outstanding		31,972,789

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Operating revenue	[1]	$ 85	$ 103.1	$ 253.6	$ 286.9
Operating Expenses
Purchased gas	[1]	2.6	23.4	7.5	52.8
Other operations and maintenance:
Affiliated suppliers		6.4	5.2	22.8	16.4
Other		10.3	8.6	30	26.7
Depreciation and amortization		10.4	9.9	30.6	30.4
Other taxes		7.6	7.3	21.7	20
Total operating expenses		37.3	54.4	112.6	146.3
Income from operations		47.7	48.7	141	140.6
Earnings from equity method investee		4.7	0	14.8	0
Other income		0.9	0.2	2.3	0.6
Interest and related charges (benefit)	[1]	(0.1)	0.1	(0.2)	0.3
Income from operations including noncontrolling interest before income taxes		53.4	48.8	158.3	140.9
Income tax expense		0	0	0	2.1
Net income including noncontrolling interest and DCG Predecessor		53.4	48.8	158.3	138.8
Less: Net income attributable to DCG Predecessor		0	0	0	2.3
Net income including noncontrolling interest		53.4	48.8	158.3	136.5
Less: Net income attributable to noncontrolling interest		29.1	30.8	88.4	89.1
Net income attributable to partners		24.3	18	69.9	47.4
Net income attributable to partners' ownership interest
General partner's interest in net income		0.7	0	1.7	(0.7)
Common Units
Net income attributable to partners' ownership interest
Net income attributable to limited partners		$ 13.8	$ 10.5	$ 40.1	$ 26.7
Net income per limited partner unit (basic and diluted)
Net income per limited partner unit (basic and diluted)		$ 0.30	$ 0.28	$ 0.88	$ 0.75
Subordinated Units
Net income attributable to partners' ownership interest
Net income attributable to limited partners		$ 9.8	$ 7.5	$ 28.1	$ 21.4
Net income per limited partner unit (basic and diluted)
Net income per limited partner unit (basic and diluted)		$ 0.30	$ 0.24	$ 0.88	$ 0.67
[1]	See Note 14 for amounts attributable to related parties.

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Current Assets
Cash and cash equivalents		$ 57.1	$ 35
Customer and other receivables		26.4	27
Affiliated receivables		6.3	6.2
Prepayments		1	10.6
Materials and supplies		12.7	12.5
Regulatory assets		2.4	1.7
Other	[1]	3.1	2.8
Total current assets		109	95.8
Investment in Equity Method Affiliate		217.9	220.5
Property, Plant and Equipment
Property, plant and equipment		4,808.3	3,845.7
Accumulated depreciation and amortization		(376.3)	(351)
Total property, plant and equipment, net		4,432	3,494.7
Deferred Charges and Other Assets
Goodwill		295.5	295.5
Intangible assets, net		14.8	15.8
Regulatory assets		4.2	2.5
Other	[1]	1.4	0.4
Total deferred charges and other assets		315.9	314.2
Total assets		5,074.8	4,125.2
Current Liabilities
Accounts payable		18.3	8.6
Payables to affiliates		6	5.2
Accrued payroll and taxes		11.7	6
Regulatory liabilities		3.8	6.7
Dominion credit facility borrowings		21.6	5.9
Deferred revenue		7.5	4.2
Natural gas imbalances	[1]	4.3	1
CPCN obligation		7.9	8
Other		15.9	14.4
Total current liabilities		97	60
Affiliated Long-Term Debt		300.8	300.8
Deferred Credits and Other Liabilities
Pension and other postretirement benefit liabilities	[1]	5.9	5
Regulatory liabilities		65.9	66.7
CPCN obligation		21.4	29
Asset retirement obligation		12.8	13
Deferred revenue		11	9.1
Other		1.2	0.6
Total deferred credits and other liabilities		118.2	123.4
Total liabilities		516	484.2
Commitments and Contingencies
Equity and Partners' Capital
Total Dominion Midstream Partners, LP partners' capital		1,519.2	1,502.6
Noncontrolling interest		3,039.6	2,138.4
Total equity and partners' capital		4,558.8	3,641
Total liabilities and equity and partners' capital		5,074.8	4,125.2
Common Units
Equity and Partners' Capital
Common unitholders and Subordinated unitholder		592	600.8
Dominion
Equity and Partners' Capital
General Partner interest - Dominion (non-economic interest)		(11.6)	(12.4)
Dominion | Common Units
Equity and Partners' Capital
Common unitholders and Subordinated unitholder		456.8	438.8
Dominion | Subordinated Units
Equity and Partners' Capital
Common unitholders and Subordinated unitholder		$ 482	$ 475.4
[1]	See Note 14 for amounts attributable to related parties.

Consolidated Balance Sheets (U4

Consolidated Balance Sheets (Unaudited) (Parenthetical) - shares	Sep. 30, 2016	Dec. 31, 2015
Common Units
Common unitholders and Subordinated unitholder - units issued	27,217,743	27,867,938
Common unitholders and Subordinated unitholder- units outstanding	27,217,743	27,867,938
Common Units | Dominion
Common unitholders and Subordinated unitholder - units issued	18,504,628	17,846,672
Common unitholders and Subordinated unitholder- units outstanding	18,504,628	17,846,672
Subordinated Units | Dominion
Common unitholders and Subordinated unitholder - units issued	31,972,789	31,972,789
Common unitholders and Subordinated unitholder- units outstanding	31,972,789	31,972,789

Consolidated Statement of Equit

Consolidated Statement of Equity and Partners' Capital (Unaudited) - 9 months ended Sep. 30, 2016 - USD ($) $ in Millions	Total	Total Dominion Midstream Partners, LP Partners' Equity and Capital	Common Unitholders and Subordinated UnitholderCommon UnitsCommon Unitholders Public	Common Unitholders and Subordinated UnitholderCommon UnitsCommon Unitholder and Subordinated Unitholder- Dominion	Common Unitholders and Subordinated UnitholderSubordinated UnitsCommon Unitholder and Subordinated Unitholder- Dominion	General Partner Dominion (non-economic interest)General Partner Dominion (non-economic interest)	Noncontrolling interest
Balance at Dec. 31, 2015	$ 3,641	$ 1,502.6	$ 600.8	$ 438.8	$ 475.4	$ (12.4)	$ 2,138.4
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income including noncontrolling interest and DCG Predecessor	158.3	69.9	24	16.1	28.1	1.7	88.4
Equity contributions from Dominion	812.4	0.4				0.4	812
Purchase of common units by Dominion	0	0	(14.2)	14.2
Distributions	(53.6)	(53.6)	(18.5)	(12.3)	(21.5)	(1.3)
Unit awards (net of unearned compensation)	0.2	0.2	0.2
Other	0.5	(0.3)	(0.3)				0.8
Balance at Sep. 30, 2016	$ 4,558.8	$ 1,519.2	$ 592	$ 456.8	$ 482	$ (11.6)	$ 3,039.6

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating Activities
Net income including noncontrolling interest and DCG Predecessor	$ 158.3	$ 138.8
Adjustments to reconcile net income including noncontrolling interest and DCG Predecessor to net cash provided by operating activities:
Depreciation and amortization	30.6	30.4
Deferred income taxes	0	1.5
Other adjustments to income, net	0.9	1.5
Changes in:
Customer and other receivables	0.6	(18.3)
Prepayments	9.6	(3.8)
Accounts payable	(3)	34.5
Payables to affiliates	0.8	1.8
Accrued payroll and taxes	5.8	2.5
Other operating assets and liabilities	6.5	6.7
Net cash provided by operating activities	210.1	195.6
Investing Activities
Plant construction and other property additions	(960.6)	(850)
Other	(1.5)	(0.4)
Net cash used in investing activities	(962.1)	(850.4)
Financing Activities
Dominion credit facility borrowings, net	15.7	5.9
Contributions from Dominion	812	614.6
Other	0	(0.2)
Net cash provided by financing activities	774.1	586.4
Increase (decrease) in cash and cash equivalents	22.1	(68.4)
Cash and cash equivalents at beginning of period	35	175.4
Cash and cash equivalents at end of period	57.1	107
Significant noncash investing and financing activities:
Accrued capital expenditures	25.3	14.8
Acquisition of a noncontrolling partnership interest in Iroquois through issuance of equity	0	216
DCG Acquisition through issuance of debt and equity
Significant noncash investing and financing activities:
DCG Acquisition through issuance of debt and equity	0	500.8
Settlement of net current and deferred income tax assets
Significant noncash investing and financing activities:
Settlement of net current and deferred income tax assets and equity contributions from Dominion to relieve payables to affiliates	0	13.4
Equity contributions from Dominion to relieve payables to affiliates
Significant noncash investing and financing activities:
Settlement of net current and deferred income tax assets and equity contributions from Dominion to relieve payables to affiliates	0.4	1.7
Limited Partners | Common Units
Financing Activities
Distributions to public unitholders	(18.5)	(10.1)
Limited Partners | Dominion | Common Units
Financing Activities
Distributions to Dominion	(12.3)	(7.8)
Limited Partners | Dominion | Subordinated Units
Financing Activities
Distributions to Dominion	(21.5)	(16)
General Partner | Dominion
Financing Activities
Distributions to Dominion	$ (1.3)	$ 0

Description of Business and Bas

Description of Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	Description of Business and Basis of Presentation Description of Business Dominion Midstream is a Delaware limited partnership formed in March 2014 by Dominion MLP Holding Company, LLC and Dominion Midstream GP, LLC, both indirect wholly-owned subsidiaries of Dominion, to grow a portfolio of natural gas terminaling, processing, storage, transportation and related assets. Dominion Midstream acquired from Dominion the Preferred Equity Interest and non-economic general partner interest in Cove Point, the owner and operator of the Cove Point LNG Facility and the Cove Point Pipeline. The Preferred Equity Interest is a perpetual, non-convertible preferred equity interest entitled to Preferred Return Distributions so long as Cove Point has sufficient cash and undistributed Net Operating Income (determined on a cumulative basis from the closing of the Offering) from which to make Preferred Return Distributions. Preferred Return Distributions are made on a quarterly basis and are not cumulative. The Preferred Equity Interest is also entitled to the Additional Return Distributions. On April 1, 2015, Dominion Midstream acquired from Dominion all issued and outstanding membership interests in DCG as described further in Note 2. DCG owns and operates nearly 1,500 miles of FERC-regulated open access, transportation-only interstate natural gas pipeline in South Carolina and southeastern Georgia. On September 29, 2015, Dominion Midstream acquired a 25.93% noncontrolling partnership interest in Iroquois as described further in Note 7. Iroquois, a Delaware limited partnership, owns and operates a 416 -mile FERC-regulated interstate natural gas transmission pipeline that extends from the Canada-United States border through the states of New York and Connecticut. Basis of Presentation The contribution by Dominion to Dominion Midstream of the general partner interest in Cove Point and a portion of the Preferred Equity Interest is considered to be a reorganization of entities under common control. As a result, Dominion Midstream’s basis is equal to Dominion’s cost basis in the general partner interest in Cove Point and a portion of the Preferred Equity Interest. As discussed in Note 10, Dominion Midstream is the primary beneficiary of, and therefore consolidates, Cove Point. As such, Dominion Midstream’s investment in the Preferred Equity Interest and Cove Point's preferred equity interest are eliminated in consolidation. Dominion's retained common equity interest in Cove Point is reflected as noncontrolling interest. The DCG Acquisition is considered to be a reorganization of entities under common control. As a result, Dominion Midstream’s basis in DCG is equal to Dominion’s cost basis in the assets and liabilities of DCG. On April 1, 2015, DCG became a wholly-owned subsidiary of Dominion Midstream and is therefore consolidated by Dominion Midstream. The accompanying financial statements and related notes have been retrospectively adjusted to include the historical results and financial position of DCG beginning January 31, 2015, the inception date of common control. The financial statements for all periods presented include costs for certain general, administrative and corporate expenses assigned by DRS or DCGS (Dominion Payroll prior to January 1, 2016) to Dominion Midstream on the basis of direct and allocated methods in accordance with Dominion Midstream's services agreements with DRS or DCGS (Dominion Payroll prior to January 1, 2016). Where costs incurred cannot be determined by specific identification, the costs are allocated based on the proportional level of effort devoted by DRS or DCGS (Dominion Payroll prior to January 1, 2016) resources that is attributable to the entities, determined by reference to number of employees, salaries and wages and other similar measures for the relevant DRS or DCGS (Dominion Payroll prior to January 1, 2016) department. Management believes the assumptions and methodologies underlying the allocation of general corporate overhead expenses are reasonable.

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2016
Business Combinations [Abstract]
Acquisitions	Acquisitions DCG On April 1, 2015, Dominion Midstream entered into a Purchase, Sale and Contribution Agreement with Dominion pursuant to which Dominion Midstream purchased from Dominion all of the issued and outstanding membership interests of DCG in exchange for total consideration of approximately $500.8 million , as adjusted for working capital. Total consideration to Dominion consisted of the issuance of a two -year $300.8 million senior unsecured promissory note, as adjusted for working capital, payable to Dominion at an annual interest rate of 0.6% , and 5,112,139 common units, valued at $200.0 million , representing limited partner interests in Dominion Midstream, to Dominion. The number of units was based on the volume weighted average trading price of Dominion Midstream's common units for the 10 trading days prior to April 1, 2015, or $39.12 per unit. For the nine months ended September 30, 2016, total transition costs of $1.3 million were expensed as incurred to operations and maintenance expense in the Consolidated Statements of Income. These costs were paid by Dominion, and Dominion Midstream subsequently reimbursed Dominion. There were no such costs incurred during the three months ended September 30, 2016. Subsequent to the DCG Acquisition through September 30, 2015, total transaction and transition costs of $1.5 million were expensed as incurred to operations and maintenance expense in the Consolidated Statements of Income, including $0.5 million for the three months ended September 30, 2015. These costs were paid by Dominion. Dominion did not seek reimbursement for $0.7 million of such costs incurred subsequent to the DCG Acquisition in 2015, and accordingly Dominion Midstream recognized a capital contribution by the general partner. The DCG Acquisition supports the expansion of Dominion Midstream's portfolio of natural gas terminaling, processing, storage, transportation and related assets. The contribution of DCG by Dominion to Dominion Midstream is considered to be a reorganization of entities under common control. Accordingly, Dominion Midstream's net investment in DCG is recorded at Dominion's historical cost of $501.6 million as of April 1, 2015. Common control began on January 31, 2015, concurrent with Dominion's acquisition of DCG from SCANA, which was accounted for using the acquisition method of accounting. Accordingly, the Consolidated Financial Statements of Dominion Midstream reflect DCG's financial results beginning January 31, 2015. In connection with the DCG Acquisition, Dominion Midstream entered into a registration rights agreement with Dominion pursuant to which Dominion Midstream must register the 5,112,139 common units issued to Dominion at its request, subject to certain terms and conditions. Additionally, at the time of Dominion's acquisition of DCG, DCG entered into services agreements and an intercompany tax sharing agreement with Dominion as described in Note 14. Iroquois On August 14, 2015, Dominion Midstream entered into contribution agreements with NG and NJNR. On September 29, 2015, pursuant to the contribution agreements, Dominion Midstream acquired a 25.93% noncontrolling partnership interest in Iroquois, consisting of NG’s 20.4% and NJNR’s 5.53% partnership interests in Iroquois and, in exchange, Dominion Midstream issued common units representing limited partnership interests in Dominion Midstream to both NG ( 6,783,373 common units) and NJNR ( 1,838,932 common units). The number of units was based on the volume-weighted average trading price of Dominion Midstream’s common units for the five trading days prior to August 14, 2015, or $33.23 per unit. The acquisition of the 25.93% noncontrolling partnership interest in Iroquois supports the expansion of Dominion Midstream’s portfolio of natural gas terminaling, processing, storage, transportation and related assets. The Iroquois investment, accounted for under the equity method, was recorded at $216.4 million based on the value of Dominion Midstream's common units at closing, including $0.4 million of external transaction costs. NG and NJNR agreed to certain transfer restrictions applicable to the 8,622,305 common units issued to them, including, with limited exceptions, a one -year lockup period following the closing of the transactions described above. In addition, at closing, Dominion Midstream entered into registration rights agreements with NG and NJNR pursuant to which Dominion Midstream was required to register the common units issued to NG and NJNR for resale when Dominion Midstream became eligible to file a registration statement on Form S-3. Such registration statement, filed on November 2, 2015, did not change the lockup periods to which NG and NJNR were subject. No market issuance of the common units is planned in connection with the transactions described above. Questar Pipeline In October 2016, Dominion Midstream, following approval by the Conflicts Committee of Dominion Midstream GP, LLC, its general partner, entered into the Questar Pipeline Contribution Agreement to acquire Questar Pipeline from Dominion. Upon closing of the agreement, expected by the end of 2016, Dominion Midstream will become the owner of all of the issued and outstanding membership interests of Questar Pipeline in exchange for consideration consisting of: (1) common units with a value between $100.0 million and $425.0 million with the actual number of Dominion Midstream common units to be issued to Dominion to be determined by the volume-weighted average trading price of Dominion Midstream's common units on the NYSE for the 10 -day trading period immediately preceding closing, (2) 11,365,628 convertible preferred units with a value of $300.0 million and (3) cash between $565.0 million and $890.0 million , $300.0 million of which is treated as a debt-financed distribution, for total consideration of $1.29 billion . In addition, Questar Pipeline's debt of $435.0 million is expected to remain outstanding. As a result of the transaction, Dominion Midstream will own 100% of the membership interests in Questar Pipeline and will thereafter consolidate Questar Pipeline in its financial statements. Because the contribution of Questar Pipeline by Dominion to Dominion Midstream is considered a reorganization of entities under common control, Questar Pipeline's assets and liabilities will be recorded in Dominion Midstream's consolidated financial statements at Dominion’s historical cost. Common control began on September 16, 2016, concurrent with Dominion's acquisition of Dominion Questar, which was accounted for using the acquisition method of accounting. To facilitate the financing of the anticipated acquisition of Questar Pipeline, Dominion Midstream completed a public issuance of 15,525,000 common units, which included a 2,025,000 common unit over-allotment option that was exercised in full by the underwriters, resulting in proceeds of $347.6 million , net of offering costs of $12.6 million , on November 3, 2016. In addition, in October 2016, Dominion Midstream entered into an agreement for the private placement of 5,990,633 common units with a value of $137.5 million and convertible preferred units with a value between $450.0 million and $600.0 million upon closing. Also in October 2016, Dominion Midstream entered into an agreement providing for a $300.0 million three -year senior unsecured term loan, with a variable interest rate, which will fund upon closing of the acquisition. The key terms of the senior unsecured term loan include limitations on the incurrence of additional indebtedness by Dominion Midstream's subsidiaries, a requirement that amounts due and payable under the term loan agreement be paid prior to Dominion Midstream making any distributions to unitholders and the maintenance of a quarterly leverage ratio not greater than 5.0 to 1.0 (or during the period following certain acquisitions, 5.50 to 1.0). If Dominion Midstream fails to make payments under the term loan or becomes subject to bankruptcy or other insolvency proceedings, these covenants could result in the acceleration of principal and interest payments and restrictions on distributions to unitholders. Offering expenses associated with the private placement of common units and convertible preferred units and the term loan agreement may be paid through a draw on the existing revolving credit facility with Dominion. As a condition to closing under the Questar Pipeline Contribution Agreement, Dominion Midstream is required to repay the outstanding $300.8 million senior unsecured promissory note payable to Dominion and to repurchase 6,656,839 common units from Dominion. In connection with the anticipated acquisition of Questar Pipeline, total transaction and transition costs of $0.4 million were expensed as incurred to operations and maintenance expense in the Consolidated Statements of Income, including $0.3 million for the three months ended September 30, 2016. These costs were paid by Dominion and Dominion did not seek reimbursement. Accordingly, Dominion Midstream recognized an equity contribution from the general partner. Questar Pipeline operates interstate natural gas pipelines and storage facilities in the western United States, providing natural gas transportation and underground storage services in Utah, Wyoming and Colorado. As of September 30, 2016, Questar Pipeline's natural gas system consisted of nearly 2,200 miles of interstate pipeline and nearly 58 billion cubic feet of working gas storage capacity. Questar Pipeline's core transportation system is strategically located near large reserves of natural gas in six major Rocky Mountain producing areas. Questar Pipeline transports natural gas from these producing areas to other major pipeline systems, Questar Gas Company's distribution system and other utility systems. Questar Pipeline operates and owns 50% of White River Hub, LLC, a FERC-regulated transporter of natural gas, in western Colorado, which is accounted for under the equity method. Questar Pipeline also owns gathering lines and processing facilities in Utah, through which it provides gas-processing services. The anticipated acquisition of Questar Pipeline supports the expansion of Dominion Midstream's portfolio of natural gas terminaling, processing, storage, transportation and related assets.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Interim Financial Information and Estimates As permitted by the rules and regulations of the SEC, Dominion Midstream's accompanying unaudited Consolidated Financial Statements exclude certain footnote disclosures normally included in annual audited consolidated financial statements prepared in accordance with GAAP. These unaudited Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements and Notes in Dominion Midstream’s Annual Report on Form 10-K for the year ended December 31, 2015. In the opinion of management, the accompanying unaudited Consolidated Financial Statements contain all adjustments necessary to present fairly Dominion Midstream's financial position at September 30, 2016, its results of operations for the three and nine months ended September 30, 2016 and 2015, its cash flows for the nine months ended September 30, 2016 and 2015 and changes in equity for the nine months ended September 30, 2016. Such adjustments are normal and recurring in nature unless otherwise noted. Dominion Midstream makes certain estimates and assumptions in preparing its Consolidated Financial Statements in accordance with GAAP. These estimates and assumptions affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses for the periods presented. Actual results may differ from those estimates. The results of operations for interim periods are not necessarily indicative of the results expected for the full year. Information for quarterly periods is affected by seasonal variations in sales, rate changes, purchased gas expenses and other factors. Restricted Cash In October 2016, Cove Point fully funded a distribution reserve of $25.0 million , sufficient to pay two quarters of Preferred Return Distributions.

Net Income Per Limited Partner

Net Income Per Limited Partner Unit	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Net Income Per Limited Partner Unit	Net Income Per Limited Partner Unit Net income per limited partner unit applicable to common and subordinated units is computed by dividing the respective limited partners’ interest in net income attributable to Dominion Midstream, after deducting any incentive distributions, by the weighted average number of common units and subordinated units outstanding. Because Dominion Midstream has more than one class of participating securities, the two-class method is used when calculating the net income per unit applicable to limited partners. The classes of participating securities include common units, subordinated units and IDRs. Dominion Midstream’s net income is allocated to the limited partners in accordance with their respective partnership interests, after giving effect to priority income allocations for incentive distributions, if any, to Dominion, the holder of the IDRs, pursuant to the partnership agreement. The distributions are declared and paid following the close of each quarter. Earnings in excess of distributions are allocated to the limited partners based on their respective ownership interests. Payments made to Dominion Midstream's unitholders are determined in relation to actual distributions declared and are not based on the net income allocations used in the calculation of earnings per limited partner unit. Diluted net income per limited partner unit is the same as basic net income per limited partner unit as there were no potentially dilutive common or subordinated units outstanding at September 30, 2016 and 2015. The calculation of net income per limited partner unit is as follows: Three Months Ended September 30, Nine Months Ended September 30, 2016 2016 (millions) Net income attributable to partners $ 24.3 $ 69.9 Less: General partner allocation (1) (0.3 ) (0.4 ) Distributions declared on (2) : IDRs (3) 1.0 2.1 Common unitholders 11.3 32.3 Subordinated unitholders 7.9 22.6 Total distributions declared 20.2 57.0 Undistributed earnings $ 4.4 $ 13.3 (1) See Note 2 for further information. (2) On October 21, 2016, the Board of Directors of our general partner declared a quarterly cash distribution of $0.2475 per unit, totaling $24.3 million for the three months ended September 30, 2016. This distribution will be paid on November 15, 2016 to unitholders of record on November 4, 2016. The amount of distributions declared shown above is based on the units outstanding at September 30, 2016, and therefore excludes $3.9 million of distributions, and a corresponding $0.2 million of additional IDRs, that will be paid on 15,525,000 common units issued to the public on November 3, 2016 in connection with Dominion Midstream's anticipated acquisition of Questar Pipeline. See Note 2 for further information. On July 22, 2016, the Board of Directors of our general partner declared a quarterly cash distribution of $0.2355 per unit, totaling $19.0 million for the three months ended June 30, 2016. This distribution was paid on August 15, 2016 to unitholders of record on August 5, 2016. On April 19, 2016, the Board of Directors of our general partner declared a quarterly cash distribution of $0.2245 per unit, totaling $17.8 million for the three months ended March 31, 2016. This distribution was paid on May 13, 2016 to unitholders of record on May 3, 2016. (3) Dominion is a non-economic general partner that holds all of the IDRs. Three Months Ended September 30, Nine Months Ended September 30, 2015 2015 (millions) Net income attributable to partners $ 18.0 $ 47.4 Less: General partner allocation (1) : — (0.7 ) Distributions declared on (2) : IDRs (3) — — Common unitholders 9.1 22.5 Subordinated unitholders 6.4 18.0 Total distributions declared 15.5 40.5 Undistributed earnings $ 2.5 $ 7.6 (1) See Note 2 for further information. (2) On October 23, 2015, the Board of Directors of our general partner declared a quarterly cash distribution of $0.2000 per unit, totaling $15.5 million for the three months ended September 30, 2015. This distribution was paid on November 13, 2015 to unitholders of record on November 3, 2015. On July 17, 2015, the Board of Directors of our general partner declared a quarterly cash distribution of $0.1875 per unit, totaling $12.9 million , for the three months ended June 30, 2015. This distribution was paid on August 14, 2015 to unitholders of record on August 4, 2015. The amount of distributions declared shown above is based on the units outstanding at June 30, 2015. On April 22, 2015, the Board of Directors of our general partner declared a quarterly cash distribution of $0.1750 per unit, totaling $12.1 million for the three months ended March 31, 2015. This distribution was paid on May 15, 2015 to unitholders of record on May 5, 2015. (3) Dominion is a non-economic general partner that holds all of the IDRs. Basic and diluted net income per limited partner unit Common Units Subordinated Units General Partner Total (millions, except for weighted average units and per unit data) Three Months Ended September 30, 2016 General partner allocation $ — $ — $ (0.3 ) $ (0.3 ) Distributions declared 11.3 7.9 1.0 20.2 Undistributed earnings 2.5 1.9 — 4.4 Net income attributable to partners $ 13.8 $ 9.8 $ 0.7 $ 24.3 Weighted average units outstanding 45,722,371 31,972,789 Net income per limited partner unit $ 0.30 $ 0.30 Nine Months Ended September 30, 2016 General partner allocation $ — $ — $ (0.4 ) $ (0.4 ) Distributions declared 32.3 22.6 2.1 57.0 Undistributed earnings 7.8 5.5 — 13.3 Net income attributable to partners $ 40.1 $ 28.1 $ 1.7 $ 69.9 Weighted average units outstanding 45,722,286 31,972,789 Net income per limited partner unit $ 0.88 $ 0.88 Basic and diluted net income per limited partner unit Common Units Subordinated Units General Partner Total (millions, except for weighted average units and per unit data) Three Months Ended September 30, 2015 Distributions declared $ 9.1 $ 6.4 $ — $ 15.5 Undistributed earnings 1.3 1.2 — 2.5 Net income attributable to partners $ 10.4 $ 7.6 $ — $ 18.0 Weighted average units outstanding 37,279,747 31,972,789 Net income per limited partner unit $ 0.28 $ 0.24 Nine Months Ended September 30, 2015 General partner allocation $ — $ — $ (0.7 ) $ (0.7 ) Distributions declared 22.5 18.0 — 40.5 Undistributed earnings 4.0 3.6 — 7.6 Net income attributable to partners $ 26.5 $ 21.6 $ (0.7 ) $ 47.4 Weighted average units outstanding 35,470,133 31,972,789 Net income per limited partner unit $ 0.75 $ 0.67

Unit Activity

Unit Activity	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Unit Activity	Unit Activity Activity in the number of units was as follows: Common Public Dominion Subordinated General Partner Total (non-economic interest) Balance at December 31, 2015 27,867,938 17,846,672 31,972,789 — 77,687,399 Unit-based compensation 7,761 — — — 7,761 Dominion purchase of common units (1) (657,956 ) 657,956 — — — Balance at September 30, 2016 27,217,743 18,504,628 31,972,789 — 77,695,160 (1) These shares were purchased by Dominion as part of Dominion's program initiated in September 2015, which expired in September 2016, to purchase from the market up to $50.0 million of common units representing limited partner interests in Dominion Midstream at the discretion of Dominion's management.

Operating Revenue

Operating Revenue	9 Months Ended
	Sep. 30, 2016
Revenue Recognition [Abstract]
Operating Revenue	Operating Revenue Dominion Midstream's operating revenue consists of the following: Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 (millions) Gas transportation and storage $ 81.0 $ 78.1 $ 241.7 $ 231.7 Other 4.0 25.0 11.9 55.2 Total operating revenue $ 85.0 $ 103.1 $ 253.6 $ 286.9

Equity Method Investments

Equity Method Investments	9 Months Ended
	Sep. 30, 2016
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	Equity Method Investments The Consolidated Financial Statements include Dominion Midstream's 25.93% noncontrolling partnership interest in Iroquois, which is accounted for under the equity method. See further discussion of Iroquois in Notes 1 and 10. During the three and nine months ended September 30, 2016, Dominion Midstream received distributions of $5.7 million and $17.4 million , respectively, from Iroquois. At September 30, 2016, the carrying amount of Dominion Midstream’s investment of $217.9 million exceeded its share of underlying equity in net assets by approximately $122.9 million . The difference reflects equity method goodwill and is not being amortized. Summarized financial information provided to us by Iroquois for 100% of Iroquois for the three and nine months ended September 30, 2016 is presented below. Three Months Ended September 30, Nine Months Ended September 30, (in millions) 2016 2016 Revenues $ 45.5 $ 145.2 Operating income 23.1 74.3 Net income 18.9 61.6

Regulatory Assets and Liabiliti

Regulatory Assets and Liabilities	9 Months Ended
	Sep. 30, 2016
Regulated Operations [Abstract]
Regulatory Assets and Liabilities	Regulatory Assets and Liabilities Regulatory assets and liabilities include the following: September 30, 2016 December 31, 2015 (millions) Regulatory assets: Unrecovered gas costs (1) $ 2.1 $ 1.4 Other 0.3 0.3 Regulatory assets-current 2.4 1.7 Income taxes recoverable through future rates (2) 3.3 2.5 Other 0.9 — Regulatory assets-non-current 4.2 2.5 Total regulatory assets $ 6.6 $ 4.2 Regulatory liabilities: Overrecovered gas costs (1) $ 0.2 $ 0.1 LNG cargo obligations (3) 0.6 3.0 Customer bankruptcy settlement (4) 2.9 3.1 Other 0.1 0.5 Regulatory liabilities-current 3.8 6.7 Provision for future cost of removal (5) 47.4 45.7 Customer bankruptcy settlement (4) 18.3 20.5 Other 0.2 0.5 Regulatory liabilities-non-current 65.9 66.7 Total regulatory liabilities $ 69.7 $ 73.4 (1) Reflects unrecovered/overrecovered gas costs, which are subject to annual filings with FERC. (2) Amounts to be recovered through future rates to pay income taxes that become payable by unitholders when rate revenue is provided to recover AFUDC-equity when such amounts are recovered through book depreciation. (3) Reflects obligations to the Import Shippers for LNG cargo received. See Note 12 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2015 for further information. (4) Primarily represents the balance of proceeds from the monetization of a bankruptcy claim acquired as part of the DCG Acquisition, which is being amortized into operating revenue through February 2024. (5) Rates charged to customers include a provision for the cost of future activities to remove assets that are expected to be incurred at the time of retirement. At September 30, 2016, approximately $3.3 million of regulatory assets represented past expenditures on which Dominion Midstream does not currently earn a return. These expenditures are expected to be recovered within two years.

Regulatory Matters

Regulatory Matters	9 Months Ended
	Sep. 30, 2016
Regulated Operations [Abstract]
Regulatory Matters	Regulatory Matters FERC regulates the transportation and sale for resale of natural gas in interstate commerce under the NGA and the Natural Gas Policy Act of 1978, as amended. Under the NGA, FERC has authority over rates, terms and conditions of services performed by Cove Point and DCG. FERC also has jurisdiction over siting, construction and operation of natural gas import facilities and interstate natural gas pipeline facilities. Other than the following matter, there have been no significant developments regarding the pending regulatory matters disclosed in Note 12 to the Consolidated Financial Statements in Dominion Midstream’s Annual Report on Form 10-K for the year ended December 31, 2015 and Note 9 to the Consolidated Financial Statements in Dominion Midstream’s Quarterly Reports on Form 10-Q for the quarters ended March 31, 2016 and June 30, 2016. Prior to importing or exporting LNG, Cove Point must receive approvals from the Department of Energy. In September 2013, the Department of Energy granted non-free trade agreement authorization approval for the export of up to 0.77 bcfe/day of natural gas to countries that do not have a free trade agreement for trade in natural gas. In June 2016, a party filed a petition for review of this approval in the United States Court of Appeals for the District of Columbia Circuit. This case is pending.

Variable Interest Entities

Variable Interest Entities	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	Variable Interest Entities The primary beneficiary of a VIE is required to consolidate the VIE and to disclose certain information about its significant variable interests in the VIE. The primary beneficiary of a VIE is the entity that has both: (1) the power to direct the activities that most significantly impact the entity’s economic performance and (2) the obligation to absorb losses or receive benefits from the entity that could potentially be significant to the VIE. Cove Point Dominion Midstream concluded that Cove Point is a VIE due to the limited partners lacking the characteristics of a controlling financial interest. Dominion Midstream is the primary beneficiary of Cove Point as it has the power to direct the activities that most significantly impact its economic performance as well as the obligation to absorb losses and benefits which could be significant to it. Iroquois Dominion Midstream previously concluded that Iroquois was a VIE because a non-affiliated Iroquois equity holder had the ability during a limited period of time to transfer its ownership interests to another Iroquois equity holder or its affiliate. At the end of the first quarter of 2016, such right no longer existed and Dominion Midstream concluded that Iroquois is no longer a VIE. DRS, DCGS and Dominion Payroll In connection with the Offering, our general partner entered into a services agreement with DRS. DRS provides administrative, management and other services to Dominion and its subsidiaries as a subsidiary service company. From time to time and at the option of our general partner, our general partner will request that DRS provide, and reimburse DRS for the cost of providing, such administrative, management and other services as it deems necessary or appropriate for our operations. We will reimburse our general partner and its affiliates for the associated costs of obtaining these services. For the three and nine months ended September 30, 2016, these costs were $0.3 million and $0.9 million , respectively. For the three and nine months ended September 30, 2015, these costs were $0.2 million and $0.6 million , respectively. Additionally, in connection with Dominion’s acquisition of DCG, DCG entered into services agreements beginning February 1, 2015 with DRS, for similar services as described above, and with Dominion Payroll, which provides human resources and operations services to Dominion and its subsidiaries as a subsidiary service company. Effective January 1, 2016, DCGS provides these services to Dominion Midstream with Dominion Payroll no longer providing any services to Dominion Midstream. Dominion Midstream purchased shared services from DRS and DCGS of approximately $6.3 million and $3.2 million for the three months ended September 30, 2016, respectively, and $18.8 million and $12.1 million for the nine months ended September 30, 2016, respectively. Dominion Midstream purchased shared services from DRS and Dominion Payroll of approximately $3.6 million and $3.2 million for the three months ended September 30, 2015, respectively, and $11.4 million and $8.7 million for the nine months ended September 30, 2015, respectively. The Consolidated Balance Sheets at September 30, 2016 and December 31, 2015 include amounts due from Dominion Midstream to DRS, DCGS and Dominion Payroll of approximately $3.3 million and $2.8 million , respectively. Dominion Midstream determined that neither it nor any of its consolidated entities is the primary beneficiary of DRS, DCGS or Dominion Payroll, as neither it nor any of its consolidated entities has both the power to direct the activities that most significantly impact their economic performance as well as the obligation to absorb losses and benefits which could be significant to them. Neither Dominion Midstream nor any of its consolidated entities has any obligation to absorb more than its allocated share of DRS, DCGS or Dominion Payroll costs.

Affiliated Long-Term Debt

Affiliated Long-Term Debt	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Affiliated Long-Term Debt	Affiliated Long-Term Debt In connection with the DCG Acquisition, Dominion Midstream issued a two -year, $300.8 million senior unsecured promissory note payable to Dominion, as adjusted for working capital, at an annual fixed interest rate of 0.6% . Interest on the note is payable quarterly, and all principal and accrued interest is due and payable at maturity on April 1, 2017, which under certain conditions can be extended at the option of Dominion Midstream to October 1, 2017. As a result of the financing activity associated with the anticipated acquisition of Questar Pipeline described in Note 2, the affiliated long-term debt has been classified as a noncurrent liability in the Consolidated Balance Sheet at September 30, 2016. Interest charges related to Dominion Midstream's borrowing from Dominion were $0.5 million and $1.4 million for the three and nine months ended September 30, 2016, respectively, and $0.5 million and $1.0 million for the three and nine months ended September 30, 2015, respectively. At September 30, 2016 and December 31, 2015, accrued interest payable to Dominion of $0.5 million was recorded in payables to affiliates on the Consolidated Balance Sheets. The debt instrument described above is reported at historical cost. At September 30, 2016, the fair value of Dominion Midstream's outstanding debt was $300.6 million . The estimated fair value has been determined using available market information and valuation methodologies considered appropriate by management. The fair value was calculated using market interest rates currently available for issuance of debt with similar terms and remaining maturities. The fair value measurement is classified as Level 2. The key terms of the note payable to Dominion include a prohibition on the incurrence of additional indebtedness (other than under the credit facility with Dominion discussed in Note 14 or in connection with the repayment of outstanding debt, as is expected in connection with the anticipated acquisition of Questar Pipeline) and a negative pledge applicable to liens on the assets of Dominion Midstream, but which does not apply to the assets of subsidiaries of Dominion Midstream. The note payable does not include any financial covenants. If Dominion Midstream fails to make payments under the note payable or becomes subject to bankruptcy or other insolvency proceedings, Dominion may accelerate Dominion Midstream’s payment obligations under the note payable.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies As a result of issues generated in the ordinary course of business, Dominion Midstream is involved in legal proceedings before various courts and is periodically subject to governmental examinations (including by FERC), inquiries and investigations. Certain legal proceedings and governmental examinations involve demands for unspecified amounts of damages, are in an initial procedural phase, involve uncertainty as to the outcome of pending appeals or motions, or involve significant factual issues that need to be resolved, such that it is not possible for Dominion Midstream to estimate a range of possible loss. For such matters that Dominion Midstream cannot estimate, a statement to this effect is made in the description of the matter. Other matters may have progressed sufficiently through the litigation or investigative processes such that Dominion Midstream is able to estimate a range of possible loss. For legal proceedings and governmental examinations for which Dominion Midstream is able to reasonably estimate a range of possible losses, an estimated range of possible loss is provided, in excess of the accrued liability (if any) for such matters. Estimated ranges of loss are inclusive of legal fees and net of any anticipated insurance recoveries. Any estimated range is based on currently available information and involves elements of judgment and significant uncertainties. Any accrued liability is recorded on a gross basis with a receivable also recorded for any probable insurance recoveries. Any estimated range of possible loss may not represent Dominion Midstream’s maximum possible loss exposure. The circumstances of such legal proceedings and governmental examinations will change from time to time and actual results may vary significantly from the current estimate. Management does not anticipate that the liabilities, if any, arising from such proceedings would have a material effect on Dominion Midstream’s financial position, liquidity or results of operations. Cove Point Natural Heritage Trust Under the terms of the 2005 Agreement, Cove Point is required to make an annual contribution to the Cove Point Natural Heritage Trust, an affiliated non-profit trust focused on the preservation and protection of ecologically sensitive sites at or near Cove Point, of $0.3 million for each year the facility is in operation. These annual payments are recorded in other operations and maintenance expense in the Consolidated Statements of Income. If Cove Point voluntarily tenders title according to the terms of this agreement, no contributions are required. There are no current plans to voluntarily tender title to the Cove Point site. Surety Bonds At September 30, 2016, Cove Point had purchased $9.8 million of surety bonds. Under the terms of surety bonds, Cove Point is obligated to indemnify the respective surety bond company for any amounts paid. Lease Commitments Dominion Midstream leases various facilities, vehicles and equipment under operating lease arrangements, the majority of which include terms of one year or less, require payments on a monthly or annual basis and can be canceled at any time. Rental expense for Dominion Midstream totaled $0.7 million and $2.3 million for the three and nine months ended September 30, 2016, respectively, and $0.7 million and $2.1 million for the three and nine months ended September 30, 2015, respectively. The majority of rent expense is included within other operations and maintenance expense in the Consolidated Statements of Income.

Credit Risk

Credit Risk	9 Months Ended
	Sep. 30, 2016
Risks and Uncertainties [Abstract]
Credit Risk	Credit Risk Credit risk is the risk of financial loss if counterparties fail to perform their contractual obligations. In order to minimize overall credit risk, credit policies are maintained, including the evaluation of counterparty financial condition. In addition, counterparties may make available collateral, including letters of credit, payment guarantees or cash deposits. Dominion Midstream provides service to approximately 70 customers, including the Storage Customers, marketers or end users and the Import Shippers. The two largest customers comprised approximately 69% and 70% of the total transportation and storage revenues for the three and nine months ended September 30, 2016, respectively, with Dominion Midstream's largest customer representing approximately 54% of such amounts in each period. The two largest customers comprised approximately 71% of the total transportation and storage revenues for each of the three and nine months ended September 30, 2015, with Dominion Midstream's largest customer representing approximately 56% and 57% of such amounts in each period, respectively. Dominion Midstream maintains a provision for credit losses based on factors surrounding the credit risk of its customers, historical trends and other information. At September 30, 2016 and December 31, 2015, the provision for credit losses was less than $0.1 million . Management believes, based on credit policies and the September 30, 2016 provision for credit losses, that it is unlikely that a material adverse effect on financial position, results of operations or cash flows would occur as a result of counterparty nonperformance.

Related-Party Transactions

Related-Party Transactions	9 Months Ended
	Sep. 30, 2016
Related Party Transactions [Abstract]
Related-Party Transactions	Related-Party Transactions Dominion Midstream engages in related-party transactions primarily with other Dominion subsidiaries (affiliates), including our general partner. Dominion Midstream's receivable and payable balances with affiliates are settled based on contractual terms or on a monthly basis, depending on the nature of the underlying transactions. Cove Point participates in certain Dominion benefit plans as described in Note 16 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2015. In Dominion Midstream's Consolidated Balance Sheets at September 30, 2016 and December 31, 2015, amounts due to Dominion associated with these benefit plans included in pension and other postretirement benefit liabilities were $5.9 million and $5.0 million , respectively, and amounts due from Dominion at September 30, 2016 included in deferred charges and other assets were $0.7 million . There were no such amounts due from Dominion at December 31, 2015. Transactions related to the DCG Acquisition and the anticipated acquisition of Questar Pipeline are described in Notes 2 and 11. A discussion of the remaining significant related party transactions follows. Transactions with Affiliates DRS provides accounting, legal, finance and certain administrative and technical services to Dominion Midstream. Effective January 1, 2016, DCGS provides human resources and operations services to Dominion Midstream as a subsidiary service company. Prior to January 1, 2016, Dominion Payroll provided human resources and operations services to Dominion Midstream as a subsidiary service company. Refer to Note 10 for further information. Dominion may seek reimbursement from DCG for costs incurred related to Dominion's transition services agreement with SCANA to provide administrative functions related to DCG. For the three and nine months ended September 30, 2016, DCG reimbursed Dominion a total of $0.2 million and $1.4 million for such costs. Subsequent to the DCG Acquisition through September 30, 2015, DCG reimbursed Dominion a total of $2.1 million for such costs, including $1.0 million for the three months ended September 30, 2015. Dominion Midstream provides transportation services to affiliates and affiliates provide goods and services to Dominion Midstream. Affiliated transactions are presented below: Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 (millions) Sales of natural gas transportation services to affiliates $ 0.5 $ 0.6 $ 1.4 $ 1.7 Purchased gas from affiliates 0.1 0.1 0.2 0.4 Goods and services provided by affiliates to Dominion Midstream (1) 12.2 8.6 37.0 25.3 (1) Includes $5.8 million and $14.2 million of capitalized expenditures for the three and nine months ended September 30, 2016, and $3.4 million and $8.9 million for the three and nine months ended September 30, 2015, respectively. Dominion Credit Facility In connection with the Offering, Dominion Midstream entered into a credit facility with Dominion with a borrowing capacity of $300 million . A summary of certain key terms of the credit facility with Dominion is included in Note 20 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2015. At September 30, 2016 and December 31, 2015, $21.6 million and $5.9 million was outstanding against the credit facility, respectively. In October 2016, Dominion Midstream drew an additional $7.3 million on the credit facility to fund capital expenditures at DCG. Outstanding borrowings are presented within current liabilities as such amounts could become payable on demand after a 90 -day termination notice provided by either party. No such notice has been provided through the date of this filing. Interest charges related to Dominion Midstream's borrowings against the facility were $0.1 million and $0.2 million for the three and nine months ended September 30, 2016, respectively, and less than $0.1 million for the three and nine months ended September 30, 2015. Income Taxes DCG participated in Dominion's intercompany tax sharing agreement from February 1, 2015 through March 31, 2015. DCG's participation in this tax sharing agreement was subsequently terminated in connection with the DCG Acquisition. At the time of the DCG Acquisition, DCG settled income taxes payable and net deferred income taxes of $13.4 million through an equity transaction with Dominion. Natural Gas Imbalances Dominion Midstream maintains natural gas imbalances with affiliates. The imbalances with affiliates are provided below: September 30, 2016 December 31, 2015 (millions) Imbalances payable to affiliates $ 1.9 $ 0.8 Imbalances receivable from affiliates (1) 0.1 — (1) Included within other current assets in the Consolidated Balance Sheets. Right of First Offer In connection with the Offering, Dominion Midstream entered into a right of first offer agreement with Dominion as described in Note 20 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2015. There have been no changes to this agreement. Contributions from Dominion For the three and nine months ended September 30, 2016, Dominion contributed $273.4 million and $812.0 million , respectively, to Cove Point. For the three and nine months ended September 30, 2015, Dominion contributed $341.5 million and $613.3 million , respectively, to Cove Point. In October 2016, Dominion contributed an additional $61.8 million to Cove Point. These contributions from Dominion to Cove Point represent funding for capital expenditures related to the Liquefaction Project. In February 2015, Dominion contributed $1.3 million in cash to DCG to fund operations. Transaction and transition costs incurred by the DCG Predecessor were attributed to Dominion Midstream and expensed in operations and maintenance expense in the Consolidated Statements of Income. At the time of the DCG Acquisition, Dominion Midstream settled amounts payable to Dominion of $1.0 million through equity contributions from Dominion. Subsequent to the DCG Acquisition through September 30, 2015, Dominion allocated transaction and transition costs related to the DCG Acquisition of $1.5 million to Dominion Midstream, of which Dominion did not seek reimbursement for $0.7 million as described further in Note 2. For the three and nine months ended September 30, 2016, Dominion allocated costs of $0.3 million and $0.4 million , respectively, to Dominion Midstream related to the anticipated acquisition of Questar Pipeline for which Dominion did not seek reimbursement.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Dominion Midstream is organized as an MLP, a pass-through entity for United States federal and state income tax purposes. Each unitholder is responsible for taking into account the unitholder’s respective share of Dominion Midstream’s items of taxable income, gain, loss and deduction in the preparation of income tax returns. Upon the closing of the Offering, Cove Point became a pass-through entity for United States federal and state income tax purposes. Effective April 1, 2015, the date of the DCG Acquisition, DCG is treated as a component of Dominion Midstream for income tax purposes. Accordingly, Dominion Midstream's Consolidated Financial Statements do not include income taxes for the period subsequent to the Offering, with the exception of income taxes attributable to the DCG Predecessor. DCG operated as a taxable corporation at the time of Dominion's acquisition of DCG. In March 2015, DCG converted to a single member limited liability company and as a result, became a disregarded entity for income tax purposes and was treated as a taxable division of its corporate parent, Dominion. Current income taxes for DCG were based on taxable income or loss, determined on a separate company basis, and, where applicable, settled in accordance with the principles of Dominion’s intercompany tax sharing agreement. The settlement of DCG’s federal and state income taxes payable and net deferred income taxes is reflected as an equity transaction in Dominion Midstream’s Consolidated Financial Statements. For the nine months ended September 30, 2016 and 2015, the statutory United States federal income tax rate reconciles to the effective income tax rate as follows: Nine Months Ended September 30, 2016 2015 United States statutory rate 35.0 % 35.0 % Partnership income not subject to income taxes (1) (35.0 ) (33.6 ) Increases resulting from: State taxes, net of federal benefit (2) — 0.1 Effective tax rate — % 1.5 % (1) Reflects the pass-through entity status of Dominion Midstream, including the operations of DCG subsequent to the DCG Acquisition, and Cove Point. (2) 2015 amounts are attributable to the operations of DCG prior to the DCG Acquisition. See Note 21 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2015 for additional information.

Operating Segment

Operating Segment	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Operating Segment	Operating Segment Dominion Midstream is organized primarily on the basis of products and services sold in the United States. Dominion Energy, Dominion Midstream's operating segment, consists of gas transportation, storage and regasification services. Dominion Midstream also reports a Corporate and Other segment. The Corporate and Other segment primarily includes items attributable to Dominion Midstream's operating segment that are not included in profit measures evaluated by executive management in assessing the segment's performance or in allocating resources. The following table presents segment information pertaining to Dominion Midstream's operations: Dominion Energy Corporate and Other Total (millions) Three Months Ended September 30, 2016 Operating revenue $ 85.0 $ — $ 85.0 Earnings from equity method investee 4.7 — 4.7 Net income (loss) including noncontrolling interest 53.7 (0.3 ) 53.4 Net income (loss) attributable to partners 24.6 (0.3 ) 24.3 Three Months Ended September 30, 2015 Operating revenue $ 103.1 $ — $ 103.1 Net income (loss) including noncontrolling interest 48.8 — 48.8 Net income (loss) attributable to partners 18.0 — 18.0 Nine Months Ended September 30, 2016 Operating revenue $ 253.6 $ — $ 253.6 Earnings from equity method investee 14.8 — 14.8 Net income (loss) including noncontrolling interest 158.7 (0.4 ) 158.3 Net income (loss) attributable to partners 70.3 (0.4 ) 69.9 Nine Months Ended September 30, 2015 Operating revenue $ 286.9 $ — $ 286.9 Net income (loss) including noncontrolling interest and DCG Predecessor 140.5 (1.7 ) 138.8 Net income (loss) including noncontrolling interest 137.2 (0.7 ) 136.5 Net income (loss) attributable to partners 48.1 (0.7 ) 47.4

Significant Accounting Polici23

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The contribution by Dominion to Dominion Midstream of the general partner interest in Cove Point and a portion of the Preferred Equity Interest is considered to be a reorganization of entities under common control. As a result, Dominion Midstream’s basis is equal to Dominion’s cost basis in the general partner interest in Cove Point and a portion of the Preferred Equity Interest. As discussed in Note 10, Dominion Midstream is the primary beneficiary of, and therefore consolidates, Cove Point. As such, Dominion Midstream’s investment in the Preferred Equity Interest and Cove Point's preferred equity interest are eliminated in consolidation. Dominion's retained common equity interest in Cove Point is reflected as noncontrolling interest. The DCG Acquisition is considered to be a reorganization of entities under common control. As a result, Dominion Midstream’s basis in DCG is equal to Dominion’s cost basis in the assets and liabilities of DCG. On April 1, 2015, DCG became a wholly-owned subsidiary of Dominion Midstream and is therefore consolidated by Dominion Midstream. The accompanying financial statements and related notes have been retrospectively adjusted to include the historical results and financial position of DCG beginning January 31, 2015, the inception date of common control. The financial statements for all periods presented include costs for certain general, administrative and corporate expenses assigned by DRS or DCGS (Dominion Payroll prior to January 1, 2016) to Dominion Midstream on the basis of direct and allocated methods in accordance with Dominion Midstream's services agreements with DRS or DCGS (Dominion Payroll prior to January 1, 2016). Where costs incurred cannot be determined by specific identification, the costs are allocated based on the proportional level of effort devoted by DRS or DCGS (Dominion Payroll prior to January 1, 2016) resources that is attributable to the entities, determined by reference to number of employees, salaries and wages and other similar measures for the relevant DRS or DCGS (Dominion Payroll prior to January 1, 2016) department. Management believes the assumptions and methodologies underlying the allocation of general corporate overhead expenses are reasonable.
Basis of Accounting	As permitted by the rules and regulations of the SEC, Dominion Midstream's accompanying unaudited Consolidated Financial Statements exclude certain footnote disclosures normally included in annual audited consolidated financial statements prepared in accordance with GAAP. These unaudited Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements and Notes in Dominion Midstream’s Annual Report on Form 10-K for the year ended December 31, 2015.
Estimates	Dominion Midstream makes certain estimates and assumptions in preparing its Consolidated Financial Statements in accordance with GAAP. These estimates and assumptions affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses for the periods presented. Actual results may differ from those estimates.

Net Income Per Limited Partne24

Net Income Per Limited Partner Unit (Tables)	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Schedule of Calculation of Earnings per Unit	The calculation of net income per limited partner unit is as follows: Three Months Ended September 30, Nine Months Ended September 30, 2016 2016 (millions) Net income attributable to partners $ 24.3 $ 69.9 Less: General partner allocation (1) (0.3 ) (0.4 ) Distributions declared on (2) : IDRs (3) 1.0 2.1 Common unitholders 11.3 32.3 Subordinated unitholders 7.9 22.6 Total distributions declared 20.2 57.0 Undistributed earnings $ 4.4 $ 13.3 (1) See Note 2 for further information. (2) On October 21, 2016, the Board of Directors of our general partner declared a quarterly cash distribution of $0.2475 per unit, totaling $24.3 million for the three months ended September 30, 2016. This distribution will be paid on November 15, 2016 to unitholders of record on November 4, 2016. The amount of distributions declared shown above is based on the units outstanding at September 30, 2016, and therefore excludes $3.9 million of distributions, and a corresponding $0.2 million of additional IDRs, that will be paid on 15,525,000 common units issued to the public on November 3, 2016 in connection with Dominion Midstream's anticipated acquisition of Questar Pipeline. See Note 2 for further information. On July 22, 2016, the Board of Directors of our general partner declared a quarterly cash distribution of $0.2355 per unit, totaling $19.0 million for the three months ended June 30, 2016. This distribution was paid on August 15, 2016 to unitholders of record on August 5, 2016. On April 19, 2016, the Board of Directors of our general partner declared a quarterly cash distribution of $0.2245 per unit, totaling $17.8 million for the three months ended March 31, 2016. This distribution was paid on May 13, 2016 to unitholders of record on May 3, 2016. (3) Dominion is a non-economic general partner that holds all of the IDRs. Three Months Ended September 30, Nine Months Ended September 30, 2015 2015 (millions) Net income attributable to partners $ 18.0 $ 47.4 Less: General partner allocation (1) : — (0.7 ) Distributions declared on (2) : IDRs (3) — — Common unitholders 9.1 22.5 Subordinated unitholders 6.4 18.0 Total distributions declared 15.5 40.5 Undistributed earnings $ 2.5 $ 7.6 (1) See Note 2 for further information. (2) On October 23, 2015, the Board of Directors of our general partner declared a quarterly cash distribution of $0.2000 per unit, totaling $15.5 million for the three months ended September 30, 2015. This distribution was paid on November 13, 2015 to unitholders of record on November 3, 2015. On July 17, 2015, the Board of Directors of our general partner declared a quarterly cash distribution of $0.1875 per unit, totaling $12.9 million , for the three months ended June 30, 2015. This distribution was paid on August 14, 2015 to unitholders of record on August 4, 2015. The amount of distributions declared shown above is based on the units outstanding at June 30, 2015. On April 22, 2015, the Board of Directors of our general partner declared a quarterly cash distribution of $0.1750 per unit, totaling $12.1 million for the three months ended March 31, 2015. This distribution was paid on May 15, 2015 to unitholders of record on May 5, 2015. (3) Dominion is a non-economic general partner that holds all of the IDRs. Basic and diluted net income per limited partner unit Common Units Subordinated Units General Partner Total (millions, except for weighted average units and per unit data) Three Months Ended September 30, 2016 General partner allocation $ — $ — $ (0.3 ) $ (0.3 ) Distributions declared 11.3 7.9 1.0 20.2 Undistributed earnings 2.5 1.9 — 4.4 Net income attributable to partners $ 13.8 $ 9.8 $ 0.7 $ 24.3 Weighted average units outstanding 45,722,371 31,972,789 Net income per limited partner unit $ 0.30 $ 0.30 Nine Months Ended September 30, 2016 General partner allocation $ — $ — $ (0.4 ) $ (0.4 ) Distributions declared 32.3 22.6 2.1 57.0 Undistributed earnings 7.8 5.5 — 13.3 Net income attributable to partners $ 40.1 $ 28.1 $ 1.7 $ 69.9 Weighted average units outstanding 45,722,286 31,972,789 Net income per limited partner unit $ 0.88 $ 0.88 Basic and diluted net income per limited partner unit Common Units Subordinated Units General Partner Total (millions, except for weighted average units and per unit data) Three Months Ended September 30, 2015 Distributions declared $ 9.1 $ 6.4 $ — $ 15.5 Undistributed earnings 1.3 1.2 — 2.5 Net income attributable to partners $ 10.4 $ 7.6 $ — $ 18.0 Weighted average units outstanding 37,279,747 31,972,789 Net income per limited partner unit $ 0.28 $ 0.24 Nine Months Ended September 30, 2015 General partner allocation $ — $ — $ (0.7 ) $ (0.7 ) Distributions declared 22.5 18.0 — 40.5 Undistributed earnings 4.0 3.6 — 7.6 Net income attributable to partners $ 26.5 $ 21.6 $ (0.7 ) $ 47.4 Weighted average units outstanding 35,470,133 31,972,789 Net income per limited partner unit $ 0.75 $ 0.67

Unit Activity (Tables)

Unit Activity (Tables)	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Schedule of Capital Units	Activity in the number of units was as follows: Common Public Dominion Subordinated General Partner Total (non-economic interest) Balance at December 31, 2015 27,867,938 17,846,672 31,972,789 — 77,687,399 Unit-based compensation 7,761 — — — 7,761 Dominion purchase of common units (1) (657,956 ) 657,956 — — — Balance at September 30, 2016 27,217,743 18,504,628 31,972,789 — 77,695,160 (1) These shares were purchased by Dominion as part of Dominion's program initiated in September 2015, which expired in September 2016, to purchase from the market up to $50.0 million of common units representing limited partner interests in Dominion Midstream at the discretion of Dominion's management.

Operating Revenue (Tables)

Operating Revenue (Tables)	9 Months Ended
	Sep. 30, 2016
Revenue Recognition [Abstract]
Operating Revenue	Dominion Midstream's operating revenue consists of the following: Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 (millions) Gas transportation and storage $ 81.0 $ 78.1 $ 241.7 $ 231.7 Other 4.0 25.0 11.9 55.2 Total operating revenue $ 85.0 $ 103.1 $ 253.6 $ 286.9

Equity Method Investments (Tabl

Equity Method Investments (Tables)	9 Months Ended
	Sep. 30, 2016
Equity Method Investments and Joint Ventures [Abstract]
Summarized Financial Information of Equity Method Investments	Summarized financial information provided to us by Iroquois for 100% of Iroquois for the three and nine months ended September 30, 2016 is presented below. Three Months Ended September 30, Nine Months Ended September 30, (in millions) 2016 2016 Revenues $ 45.5 $ 145.2 Operating income 23.1 74.3 Net income 18.9 61.6

Regulatory Assets and Liabili28

Regulatory Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2016
Regulated Operations [Abstract]
Schedule of Regulatory Assets	Regulatory assets and liabilities include the following: September 30, 2016 December 31, 2015 (millions) Regulatory assets: Unrecovered gas costs (1) $ 2.1 $ 1.4 Other 0.3 0.3 Regulatory assets-current 2.4 1.7 Income taxes recoverable through future rates (2) 3.3 2.5 Other 0.9 — Regulatory assets-non-current 4.2 2.5 Total regulatory assets $ 6.6 $ 4.2 Regulatory liabilities: Overrecovered gas costs (1) $ 0.2 $ 0.1 LNG cargo obligations (3) 0.6 3.0 Customer bankruptcy settlement (4) 2.9 3.1 Other 0.1 0.5 Regulatory liabilities-current 3.8 6.7 Provision for future cost of removal (5) 47.4 45.7 Customer bankruptcy settlement (4) 18.3 20.5 Other 0.2 0.5 Regulatory liabilities-non-current 65.9 66.7 Total regulatory liabilities $ 69.7 $ 73.4 (1) Reflects unrecovered/overrecovered gas costs, which are subject to annual filings with FERC. (2) Amounts to be recovered through future rates to pay income taxes that become payable by unitholders when rate revenue is provided to recover AFUDC-equity when such amounts are recovered through book depreciation. (3) Reflects obligations to the Import Shippers for LNG cargo received. See Note 12 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2015 for further information. (4) Primarily represents the balance of proceeds from the monetization of a bankruptcy claim acquired as part of the DCG Acquisition, which is being amortized into operating revenue through February 2024. (5) Rates charged to customers include a provision for the cost of future activities to remove assets that are expected to be incurred at the time of retirement.
Schedule of Regulatory Liabilities	Regulatory assets and liabilities include the following: September 30, 2016 December 31, 2015 (millions) Regulatory assets: Unrecovered gas costs (1) $ 2.1 $ 1.4 Other 0.3 0.3 Regulatory assets-current 2.4 1.7 Income taxes recoverable through future rates (2) 3.3 2.5 Other 0.9 — Regulatory assets-non-current 4.2 2.5 Total regulatory assets $ 6.6 $ 4.2 Regulatory liabilities: Overrecovered gas costs (1) $ 0.2 $ 0.1 LNG cargo obligations (3) 0.6 3.0 Customer bankruptcy settlement (4) 2.9 3.1 Other 0.1 0.5 Regulatory liabilities-current 3.8 6.7 Provision for future cost of removal (5) 47.4 45.7 Customer bankruptcy settlement (4) 18.3 20.5 Other 0.2 0.5 Regulatory liabilities-non-current 65.9 66.7 Total regulatory liabilities $ 69.7 $ 73.4 (1) Reflects unrecovered/overrecovered gas costs, which are subject to annual filings with FERC. (2) Amounts to be recovered through future rates to pay income taxes that become payable by unitholders when rate revenue is provided to recover AFUDC-equity when such amounts are recovered through book depreciation. (3) Reflects obligations to the Import Shippers for LNG cargo received. See Note 12 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2015 for further information. (4) Primarily represents the balance of proceeds from the monetization of a bankruptcy claim acquired as part of the DCG Acquisition, which is being amortized into operating revenue through February 2024. (5) Rates charged to customers include a provision for the cost of future activities to remove assets that are expected to be incurred at the time of retirement.

Related-Party Transactions (Tab

Related-Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2016
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	Affiliated transactions are presented below: Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 (millions) Sales of natural gas transportation services to affiliates $ 0.5 $ 0.6 $ 1.4 $ 1.7 Purchased gas from affiliates 0.1 0.1 0.2 0.4 Goods and services provided by affiliates to Dominion Midstream (1) 12.2 8.6 37.0 25.3 (1) Includes $5.8 million and $14.2 million of capitalized expenditures for the three and nine months ended September 30, 2016, and $3.4 million and $8.9 million for the three and nine months ended September 30, 2015, respectively. The imbalances with affiliates are provided below: September 30, 2016 December 31, 2015 (millions) Imbalances payable to affiliates $ 1.9 $ 0.8 Imbalances receivable from affiliates (1) 0.1 — (1) Included within other current assets in the Consolidated Balance Sheets.

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	For the nine months ended September 30, 2016 and 2015, the statutory United States federal income tax rate reconciles to the effective income tax rate as follows: Nine Months Ended September 30, 2016 2015 United States statutory rate 35.0 % 35.0 % Partnership income not subject to income taxes (1) (35.0 ) (33.6 ) Increases resulting from: State taxes, net of federal benefit (2) — 0.1 Effective tax rate — % 1.5 % (1) Reflects the pass-through entity status of Dominion Midstream, including the operations of DCG subsequent to the DCG Acquisition, and Cove Point. (2) 2015 amounts are attributable to the operations of DCG prior to the DCG Acquisition.

Operating Segment (Tables)

Operating Segment (Tables)	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	The following table presents segment information pertaining to Dominion Midstream's operations: Dominion Energy Corporate and Other Total (millions) Three Months Ended September 30, 2016 Operating revenue $ 85.0 $ — $ 85.0 Earnings from equity method investee 4.7 — 4.7 Net income (loss) including noncontrolling interest 53.7 (0.3 ) 53.4 Net income (loss) attributable to partners 24.6 (0.3 ) 24.3 Three Months Ended September 30, 2015 Operating revenue $ 103.1 $ — $ 103.1 Net income (loss) including noncontrolling interest 48.8 — 48.8 Net income (loss) attributable to partners 18.0 — 18.0 Nine Months Ended September 30, 2016 Operating revenue $ 253.6 $ — $ 253.6 Earnings from equity method investee 14.8 — 14.8 Net income (loss) including noncontrolling interest 158.7 (0.4 ) 158.3 Net income (loss) attributable to partners 70.3 (0.4 ) 69.9 Nine Months Ended September 30, 2015 Operating revenue $ 286.9 $ — $ 286.9 Net income (loss) including noncontrolling interest and DCG Predecessor 140.5 (1.7 ) 138.8 Net income (loss) including noncontrolling interest 137.2 (0.7 ) 136.5 Net income (loss) attributable to partners 48.1 (0.7 ) 47.4

Description of Business and B32

Description of Business and Basis of Presentation (Details) - mi	Sep. 29, 2015	Apr. 01, 2015	Sep. 30, 2016
Iroquois Gas Transmission System, LP | Partnership Interest
Subsidiary, Sale of Stock [Line Items]
Length of FERC regulated interstate natural gas pipeline (in miles) (nearly 1,500 miles of DCG owned and operated natural gas pipeline)	416
Partnership interest percentage acquired in Iroquois	25.93%		25.93%
Affiliates | DCG
Subsidiary, Sale of Stock [Line Items]
Length of FERC regulated interstate natural gas pipeline (in miles) (nearly 1,500 miles of DCG owned and operated natural gas pipeline)		1,500

Acquisitions (DCG) (Details)

Acquisitions (DCG) (Details) - USD ($)	Apr. 01, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2016
Business Acquisition [Line Items]
Equity contributions from Dominion					$ 812,400,000
Dominion | DCG | Affiliates
Business Acquisition [Line Items]
Total consideration	$ 500,800,000
Historical cost of assets and liabilities of DCG	$ 501,600,000
Dominion | DCG | Affiliates | Other Operations and Maintenance Expense
Business Acquisition [Line Items]
Total transaction costs associated with DCG acquisition		$ 0	$ 500,000	$ 1,500,000	$ 1,300,000
Dominion | DCG | Affiliates | Partnership Interest
Business Acquisition [Line Items]
Number of common units issued	5,112,139
Value of common units issued	$ 200,000,000
Number of trading days	10 days
Total transaction costs associated with DCG acquisition				1,500,000
Dominion | DCG | Affiliates | Partnership Interest | General Partner
Business Acquisition [Line Items]
Equity contributions from Dominion			$ 700,000	$ 700,000
Dominion | DCG | Affiliates | Partnership Interest | Weighted Average
Business Acquisition [Line Items]
Price per unit	$ 39.12
Dominion | DCG | Affiliates | Notes Payable | Senior Unsecured Promissory Note Payable
Business Acquisition [Line Items]
Term of senior unsecured promissory note payable	2 years
Senior unsecured promissory note payable	$ 300,800,000
Annual interest rate (percentage)	0.60%

Acquisitions (Iroquois) (Detail

Acquisitions (Iroquois) (Details) - Partnership Interest - Iroquois Gas Transmission System, LP - USD ($) $ / shares in Units, $ in Millions	Sep. 29, 2015	Sep. 28, 2015	Sep. 30, 2016
Business Acquisition [Line Items]
Partnership interest percentage acquired in Iroquois	25.93%		25.93%
Number of units issued in connection with the acquisition of a noncontrolling partnership interest in Iroquois	8,622,305
Number of trading days	5 days
Value of Iroquois investment	$ 216.4
External transaction costs	$ 0.4
Duration of lockup period	1 year
Weighted Average
Business Acquisition [Line Items]
Price per unit	$ 33.23
NG
Business Acquisition [Line Items]
Partnership interest percentage purchased		20.40%
Number of units issued in connection with the acquisition of a noncontrolling partnership interest in Iroquois	6,783,373
NJNR
Business Acquisition [Line Items]
Partnership interest percentage purchased		5.53%
Number of units issued in connection with the acquisition of a noncontrolling partnership interest in Iroquois	1,838,932

Acquisitions (Questar Pipeline)

Acquisitions (Questar Pipeline) (Details)		Nov. 03, 2016USD ($)shares	Oct. 31, 2016USD ($)producing_areashares	Sep. 30, 2016miMMcf	Oct. 31, 2016USD ($)producing_areashares	Dec. 31, 2016USD ($)shares	Sep. 30, 2016USD ($)	Sep. 30, 2016shares
Business Acquisition [Line Items]
Expected purchase of common units (in units) | shares	[1]							0
Questar Pipeline | Utah, Wyoming and Colorado
Business Acquisition [Line Items]
Length of FERC regulated interstate natural gas pipeline (in miles) (nearly 2,200 miles) | mi				2,200
Working gas storage capacity (bcf) (nearly 58 billion cubic feet) | MMcf				58,000
Questar Pipeline | Dominion | Affiliates
Business Acquisition [Line Items]
Total transaction and transition costs incurred during the period							$ 300,000
Questar Pipeline | Subsequent Event | Utah, Wyoming and Colorado
Business Acquisition [Line Items]
Number of Rocky Mountain producing areas | producing_area			6		6
Questar Pipeline | Subsequent Event | White River Hub, LLC | Western Colorado | FERC
Business Acquisition [Line Items]
Ownership percentage			50.00%		50.00%
Questar Pipeline | Subsequent Event | Senior unsecured term loan | Senior unsecured term loan
Business Acquisition [Line Items]
Principal amount			$ 300,000,000		$ 300,000,000
Term of senior unsecured promissory note payable					3 years
Quarterly leverage ratio					5
Quarterly leverage ratio following certain acquisitions					5.50
Questar Pipeline | Subsequent Event | Dominion | Subsidiary of Common Parent
Business Acquisition [Line Items]
Total consideration			1,290,000,000
Amount of debt expected to remain outstanding			$ 435,000,000
Ownership percentage			100.00%		100.00%
Questar Pipeline | Subsequent Event | Dominion | Subsidiary of Common Parent | Minimum
Business Acquisition [Line Items]
Amount of cash consideration			$ 565,000,000
Questar Pipeline | Subsequent Event | Dominion | Subsidiary of Common Parent | Maximum
Business Acquisition [Line Items]
Amount of cash consideration			890,000,000
Questar Pipeline | Subsequent Event | Dominion | Affiliates
Business Acquisition [Line Items]
Total transaction and transition costs			400,000		$ 400,000
Questar Pipeline | Subsequent Event | Dominion | Senior unsecured term loan | Senior unsecured term loan | Subsidiary of Common Parent
Business Acquisition [Line Items]
Amount of debt financed distribution			$ 300,000,000
Questar Pipeline | Subsequent Event | Dominion | Notes Payable | Senior Unsecured Promissory Note Payable | Affiliates | Scenario, Forecast
Business Acquisition [Line Items]
Required repayment of outstanding senior unsecured promissory note payable to Dominion						$ 300,800,000
Questar Pipeline | Subsequent Event | Common Units | Dominion | Subsidiary of Common Parent
Business Acquisition [Line Items]
Number of trading days			10 days
Questar Pipeline | Subsequent Event | Common Units | Dominion | Subsidiary of Common Parent | Minimum
Business Acquisition [Line Items]
Value of units issued			$ 100,000,000		100,000,000
Questar Pipeline | Subsequent Event | Common Units | Dominion | Subsidiary of Common Parent | Maximum
Business Acquisition [Line Items]
Value of units issued			425,000,000		425,000,000
Questar Pipeline | Subsequent Event | Common Units | Dominion | Affiliates | Scenario, Forecast
Business Acquisition [Line Items]
Expected purchase of common units (in units) | shares						6,656,839
Questar Pipeline | Subsequent Event | Convertible Preferred Units | Dominion | Subsidiary of Common Parent
Business Acquisition [Line Items]
Value of units issued			$ 300,000,000		300,000,000
Number of units issued | shares			11,365,628
Questar Pipeline | Subsequent Event | Underwritten Public Offering
Business Acquisition [Line Items]
Proceeds from public issuance		$ 347,600,000
Questar Pipeline | Subsequent Event | Underwritten Public Offering | Common Units
Business Acquisition [Line Items]
Number of common units issued | shares		15,525,000
Estimated offering costs		$ 12,600,000
Questar Pipeline | Subsequent Event | Over-Allotment Option | Common Units
Business Acquisition [Line Items]
Number of common units issued | shares		2,025,000
Questar Pipeline | Subsequent Event | Private Placement
Business Acquisition [Line Items]
Proceeds from public issuance					$ 137,500,000
Questar Pipeline | Subsequent Event | Private Placement | Common Units
Business Acquisition [Line Items]
Number of common units issued | shares					5,990,633
Questar Pipeline | Subsequent Event | Private Placement | Convertible Preferred Units | Minimum
Business Acquisition [Line Items]
Proceeds from issuance of convertible preferred units					$ 450,000,000
Questar Pipeline | Subsequent Event | Private Placement | Convertible Preferred Units | Maximum
Business Acquisition [Line Items]
Proceeds from issuance of convertible preferred units					$ 600,000,000
[1]	These shares were purchased by Dominion as part of Dominion's program initiated in September 2015, which expired in September 2016, to purchase from the market up to $50.0 million of common units representing limited partner interests in Dominion Midstream at the discretion of Dominion's management.

Significant Accounting Polici36

Significant Accounting Policies (Restricted Cash) (Details) - Subsequent Event - Cove Point - Preferred Stock - Preferred Return Distributions $ in Millions	1 Months Ended
	Oct. 31, 2016USD ($)
Restricted Cash and Cash Equivalents Items [Line Items]
Distribution reserve	$ 25
Funding period	6 months

Net Income Per Limited Partne37

Net Income Per Limited Partner Unit (Details) - USD ($) $ / shares in Units, $ in Millions	Nov. 03, 2016	Oct. 21, 2016	Jul. 22, 2016	Apr. 19, 2016	Oct. 23, 2015	Jul. 17, 2015	Apr. 22, 2015	Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2016		Sep. 30, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Potentially dilutive common or subordinated units outstanding (in units)												0		0
Net income attributable to partners								$ 24.3		$ 18		$ 69.9		$ 47.4
Less: General partner allocation								(0.3)				(0.4)		(0.7)
Distribution declared on Common and Subordinated unitholders			$ 19	$ 17.8	$ 15.5	$ 12.9	$ 12.1
Total distributions declared								20.2		15.5		57		40.5
Undistributed earnings								$ 4.4		$ 2.5		$ 13.3		$ 7.6
Quarterly distribution per unit			$ 0.2355	$ 0.2245	$ 0.2000	$ 0.1875	$ 0.1750
Subsequent Event
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Distribution declared on Common and Subordinated unitholders		$ 24.3
Quarterly distribution per unit		$ 0.2475
Subsequent Event | Questar Pipeline | Underwritten Public Offering
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
IDRs	$ 0.2
Distributions paid on common units issued	$ 3.9
Subsequent Event | Questar Pipeline | Underwritten Public Offering | Common Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Number of common units issued	15,525,000
Common Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income per limited partner unit (basic and diluted)								$ 0.30		$ 0.28		$ 0.88		$ 0.75
Subordinated Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income per limited partner unit (basic and diluted)								$ 0.30		$ 0.24		$ 0.88		$ 0.67
General Partner
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to partners								$ 0.7		$ 0		$ 1.7		$ (0.7)
Less: General partner allocation								(0.3)	[1]	0	[2]	(0.4)	[1]	(0.7)	[2]
IDRs								1	[3],[4]	0	[5],[6]	2.1	[3],[4]	0	[5],[6]
Total distributions declared								1		0		2.1		0
Undistributed earnings								0		0		0		0
Limited Partners | Common Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to partners								13.8		10.4		40.1		26.5
Less: General partner allocation								0				0		0
Distribution declared on Common and Subordinated unitholders								11.3	[4]	9.1	[6]	32.3	[4]	22.5	[6]
Total distributions declared								11.3		9.1		32.3		22.5
Undistributed earnings								$ 2.5		$ 1.3		$ 7.8		$ 4
Weighted average units outstanding								45,722,371		37,279,747		45,722,286		35,470,133
Net income per limited partner unit (basic and diluted)								$ 0.30		$ 0.28		$ 0.88		$ 0.75
Limited Partners | Subordinated Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to partners								$ 9.8		$ 7.6		$ 28.1		$ 21.6
Less: General partner allocation								0				0		0
Distribution declared on Common and Subordinated unitholders								7.9	[4]	6.4	[6]	22.6	[4]	18	[6]
Total distributions declared								7.9		6.4		22.6		18
Undistributed earnings								$ 1.9		$ 1.2		$ 5.5		$ 3.6
Weighted average units outstanding								31,972,789		31,972,789		31,972,789		31,972,789
Net income per limited partner unit (basic and diluted)								$ 0.30		$ 0.24		$ 0.88		$ 0.67
[1]	See Note 2 for further information.
[2]	See Note 2 for further information.
[3]	Dominion is a non-economic general partner that holds all of the IDRs.
[4]	On October 21, 2016, the Board of Directors of our general partner declared a quarterly cash distribution of $0.2475 per unit, totaling $24.3 million for the three months ended September 30, 2016. This distribution will be paid on November 15, 2016 to unitholders of record on November 4, 2016. The amount of distributions declared shown above is based on the units outstanding at September 30, 2016, and therefore excludes $3.9 million of distributions, and a corresponding $0.2 million of additional IDRs, that will be paid on 15,525,000 common units issued to the public on November 3, 2016 in connection with Dominion Midstream's anticipated acquisition of Questar Pipeline. See Note 2 for further information. On July 22, 2016, the Board of Directors of our general partner declared a quarterly cash distribution of $0.2355 per unit, totaling $19.0 million for the three months ended June 30, 2016. This distribution was paid on August 15, 2016 to unitholders of record on August 5, 2016. On April 19, 2016, the Board of Directors of our general partner declared a quarterly cash distribution of $0.2245 per unit, totaling $17.8 million for the three months ended March 31, 2016. This distribution was paid on May 13, 2016 to unitholders of record on May 3, 2016.
[5]	Dominion is a non-economic general partner that holds all of the IDRs.
[6]	On October 23, 2015, the Board of Directors of our general partner declared a quarterly cash distribution of $0.2000 per unit, totaling $15.5 million for the three months ended September 30, 2015. This distribution was paid on November 13, 2015 to unitholders of record on November 3, 2015. On July 17, 2015, the Board of Directors of our general partner declared a quarterly cash distribution of $0.1875 per unit, totaling $12.9 million, for the three months ended June 30, 2015. This distribution was paid on August 14, 2015 to unitholders of record on August 4, 2015. The amount of distributions declared shown above is based on the units outstanding at June 30, 2015.On April 22, 2015, the Board of Directors of our general partner declared a quarterly cash distribution of $0.1750 per unit, totaling $12.1 million for the three months ended March 31, 2015. This distribution was paid on May 15, 2015 to unitholders of record on May 5, 2015.

Unit Activity (Details)

Unit Activity (Details) - USD ($)		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at December 31, 2015 (in units)		77,687,399
Unit-based compensation (in units)		7,761
Dominion purchase of common units (in units)	[1]	0
Balance at September 30, 2016 (in units)		77,695,160
Dominion
Increase (Decrease) in Partners' Capital [Roll Forward]
Value of shares to be repurchased (in dollars)			$ 50,000,000
General Partner Dominion (non-economic interest) | General Partner Dominion (non-economic interest) | Dominion
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at December 31, 2015 (in units)		0
Unit-based compensation (in units)		0
Dominion purchase of common units (in units)	[1]	0
Balance at September 30, 2016 (in units)		0
Common Units | Common Unitholders and Subordinated Unitholder | Limited Partners
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at December 31, 2015 (in units)		27,867,938
Unit-based compensation (in units)		7,761
Dominion purchase of common units (in units)	[1]	(657,956)
Balance at September 30, 2016 (in units)		27,217,743
Common Units | Common Unitholders and Subordinated Unitholder | Limited Partners | Dominion
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at December 31, 2015 (in units)		17,846,672
Unit-based compensation (in units)		0
Dominion purchase of common units (in units)	[1]	657,956
Balance at September 30, 2016 (in units)		18,504,628
Subordinated Units | Common Unitholders and Subordinated Unitholder | Limited Partners | Dominion
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at December 31, 2015 (in units)		31,972,789
Unit-based compensation (in units)		0
Dominion purchase of common units (in units)	[1]	0
Balance at September 30, 2016 (in units)		31,972,789
[1]	These shares were purchased by Dominion as part of Dominion's program initiated in September 2015, which expired in September 2016, to purchase from the market up to $50.0 million of common units representing limited partner interests in Dominion Midstream at the discretion of Dominion's management.

Operating Revenue (Details)

Operating Revenue (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenue Recognition [Abstract]
Gas transportation and storage		$ 81	$ 78.1	$ 241.7	$ 231.7
Other		4	25	11.9	55.2
Total operating revenue	[1]	$ 85	$ 103.1	$ 253.6	$ 286.9
[1]	See Note 14 for amounts attributable to related parties.

Equity Method Investments (Deta

Equity Method Investments (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2015	Sep. 29, 2015
Schedule of Equity Method Investments [Line Items]
Investment in Equity Method Affiliate	$ 217.9	$ 217.9	$ 220.5
Iroquois Gas Transmission System, LP | Partnership Interest
Schedule of Equity Method Investments [Line Items]
Partnership interest percentage acquired in Iroquois	25.93%	25.93%		25.93%
Distributions received from Iroquois	$ 5.7	$ 17.4
Investment in Equity Method Affiliate	217.9	217.9
Amount that investment exceeded its share of underlying equity	$ 122.9	$ 122.9
Percentage of Iroquois included in summarized financial information	100.00%	100.00%
Equity Method Investment, Summarized Financial Information [Abstract]
Revenues	$ 45.5	$ 145.2
Operating income	23.1	74.3
Net income	$ 18.9	$ 61.6

Regulatory Assets and Liabili41

Regulatory Assets and Liabilities (Regulatory Assets) (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2016	Dec. 31, 2015
Regulatory Assets [Line Items]
Regulatory assets-current		$ 2.4	$ 1.7
Regulatory assets-non-current		4.2	2.5
Total regulatory assets		6.6	4.2
Past expenditures in which no return is expected		$ 3.3
Recovery period of expenditures		2 years
Unrecovered gas costs
Regulatory Assets [Line Items]
Regulatory assets-current	[1]	$ 2.1	1.4
Other
Regulatory Assets [Line Items]
Regulatory assets-current		0.3	0.3
Regulatory assets-non-current		0.9	0
Income taxes recoverable through future rates
Regulatory Assets [Line Items]
Regulatory assets-non-current	[2]	$ 3.3	$ 2.5
[1]	Reflects unrecovered/overrecovered gas costs, which are subject to annual filings with FERC.
[2]	Amounts to be recovered through future rates to pay income taxes that become payable by unitholders when rate revenue is provided to recover AFUDC-equity when such amounts are recovered through book depreciation.

Regulatory Assets and Liabili42

Regulatory Assets and Liabilities (Regulatory Liabilities) (Details) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Regulatory Liabilities [Line Items]
Regulatory liabilities-current		$ 3.8	$ 6.7
Regulatory liabilities-non-current		65.9	66.7
Total regulatory liabilities		69.7	73.4
Overrecovered gas costs
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[1]	0.2	0.1
LNG cargo obligations
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[2]	0.6	3
Customer bankruptcy settlement
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[3]	2.9	3.1
Regulatory liabilities-non-current	[3]	18.3	20.5
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities-current		0.1	0.5
Regulatory liabilities-non-current		0.2	0.5
Provision for future cost of removal
Regulatory Liabilities [Line Items]
Regulatory liabilities-non-current	[4]	$ 47.4	$ 45.7
[1]	Reflects unrecovered/overrecovered gas costs, which are subject to annual filings with FERC.
[2]	Reflects obligations to the Import Shippers for LNG cargo received. See Note 12 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2015 for further information.
[3]	Primarily represents the balance of proceeds from the monetization of a bankruptcy claim acquired as part of the DCG Acquisition, which is being amortized into operating revenue through February 2024.
[4]	Rates charged to customers include a provision for the cost of future activities to remove assets that are expected to be incurred at the time of retirement.

Variable Interest Entities (Det

Variable Interest Entities (Details) - Services provided by Affiliates - Variable Interest Entity, Not Primary Beneficiary - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
General Partner | DRS
Variable Interest Entity [Line Items]
Reimbursable costs	$ 0.3	$ 0.2	$ 0.9	$ 0.6
Affiliates
Variable Interest Entity [Line Items]
Amounts due from affiliates	3.3		3.3		$ 2.8
Affiliates | DRS
Variable Interest Entity [Line Items]
Services purchased	6.3	3.6	18.8	11.4
Affiliates | DCGS
Variable Interest Entity [Line Items]
Services purchased	$ 3.2		$ 12.1
Affiliates | Dominion Payroll
Variable Interest Entity [Line Items]
Services purchased		$ 3.2		$ 8.7

Affiliated Long-Term Debt (Deta

Affiliated Long-Term Debt (Details) - Senior Unsecured Promissory Note Payable - Notes Payable - Dominion - Affiliates - USD ($)	Apr. 01, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Debt Instrument [Line Items]
Interest charges related to borrowing from Dominion		$ 500,000	$ 500,000	$ 1,400,000	$ 1,000,000
Fair Value, Inputs, Level 2
Debt Instrument [Line Items]
Fair value of outstanding debt		300,600,000		300,600,000
Payables to Affiliates
Debt Instrument [Line Items]
Accrued interest payable to Dominion		$ 500,000		$ 500,000		$ 500,000
DCG
Debt Instrument [Line Items]
Term of senior unsecured promissory note payable	2 years
Principal amount	$ 300,800,000
Annual interest rate (percentage)	0.60%

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Other Operations and Maintenance Expense
Other Commitments [Line Items]
Rental expense	$ 700,000	$ 700,000	$ 2,300,000	$ 2,100,000
Surety Bond
Other Commitments [Line Items]
Total amount of commitment	9,800,000		$ 9,800,000
Maximum
Other Commitments [Line Items]
Operating lease arrangements term			1 year
Annual Contributions to Cove Point Natural Heritage Trust
Other Commitments [Line Items]
Total amount of commitment	300,000		$ 300,000
Annual Contributions to Cove Point Natural Heritage Trust | Minimum
Other Commitments [Line Items]
Total amount of commitment	$ 0		$ 0

Credit Risk (Details)

Credit Risk (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016USD ($)customer	Sep. 30, 2015customer	Sep. 30, 2016USD ($)customer	Sep. 30, 2015customer	Dec. 31, 2015USD ($)
Customer Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Number of customers			70
Customer Concentration Risk | Sales Revenue, Net | Two Largest Customers
Concentration Risk [Line Items]
Number of customers	2	2	2	2
Percentage of total transportation and storage revenues	69.00%	71.00%	70.00%	71.00%
Customer Concentration Risk | Sales Revenue, Net | Largest Customer
Concentration Risk [Line Items]
Percentage of total transportation and storage revenues	54.00%	56.00%	54.00%	57.00%
Credit Concentration Risk | Accounts Receivable
Concentration Risk [Line Items]
Provision for credit losses (less than $0.1 million) | $	$ 0.1		$ 0.1		$ 0.1

Related-Party Transactions (Det

Related-Party Transactions (Details) - USD ($)		Apr. 01, 2015	Oct. 31, 2016	Feb. 28, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Oct. 20, 2014
Related Party Transaction [Line Items]
Equity contributions from Dominion								$ 812,400,000
Affiliates
Related Party Transaction [Line Items]
Sales of natural gas transportation services to affiliates					$ 500,000	$ 600,000		1,400,000	$ 1,700,000
Capital expenditures					5,800,000	3,400,000		14,200,000	8,900,000
Imbalances payable to affiliates					1,900,000			1,900,000		$ 800,000
Imbalances receivable from affiliates	[1]				100,000			100,000		0
Affiliates | Reimbursement of transition services costs by affiliate | DCG
Related Party Transaction [Line Items]
Goods and services provided by affiliates					200,000	1,000,000	$ 2,100,000	1,400,000
Affiliates | Purchased gas from affiliates
Related Party Transaction [Line Items]
Purchased gas from affiliates					100,000	100,000		200,000	400,000
Affiliates | Goods and services provided by affiliates
Related Party Transaction [Line Items]
Goods and services provided by affiliates	[2]				12,200,000	8,600,000		37,000,000	25,300,000
Affiliates | Credit Facility with Dominion | Subsequent Event
Related Party Transaction [Line Items]
Amount to be drawn on Dominion credit facility			$ 7,300,000
Affiliates | Credit Facility with Dominion | Line of Credit
Related Party Transaction [Line Items]
Amount outstanding against the credit facility					21,600,000			$ 21,600,000		5,900,000
Termination notice period								90 days
Interest charges related to borrowing from Dominion (less than $0.1 million for the three and nine months ended September 30, 2015)					100,000	100,000		$ 200,000	100,000
Affiliates | Credit Facility with Dominion | IPO | Line of Credit
Related Party Transaction [Line Items]
Borrowing capacity											$ 300,000,000
Affiliates | Tax Sharing Agreement | DCG | Equity contribution with Dominion related to income taxes
Related Party Transaction [Line Items]
Settlement of income taxes payable and net deferred income taxes through an equity transaction with Dominion		$ 13,400,000
Affiliates | Capital Expenditures related to Liquefaction Project | Cove Point
Related Party Transaction [Line Items]
Amount of contribution					273,400,000	341,500,000		812,000,000	$ 613,300,000
Affiliates | Capital Expenditures related to Liquefaction Project | Cove Point | Subsequent Event
Related Party Transaction [Line Items]
Amount of contribution			$ 61,800,000
Affiliates | Contribution to Fund Operations | DCG | Predecessor
Related Party Transaction [Line Items]
Amount of contribution				$ 1,300,000
Affiliates | Dominion | DCG | Partnership Interest
Related Party Transaction [Line Items]
Equity contribution from Dominion		$ 1,000,000
Total transaction and transition costs incurred during the period							1,500,000
Affiliates | Dominion | DCG | Partnership Interest | General Partner
Related Party Transaction [Line Items]
Equity contributions from Dominion						$ 700,000	$ 700,000
Affiliates | Dominion | Questar Pipeline
Related Party Transaction [Line Items]
Total transaction and transition costs incurred during the period					300,000
Affiliates | Dominion | Questar Pipeline | Partnership Interest
Related Party Transaction [Line Items]
Total transaction and transition costs incurred during the period					300,000			400,000
Affiliates | Dominion | Pension and Other Postretirement Benefit Liabilities
Related Party Transaction [Line Items]
Amounts due to Dominion associated with benefit plans					5,900,000			5,900,000		5,000,000
Affiliates | Dominion | Other Deferred Charges and Other Assets
Related Party Transaction [Line Items]
Amounts due from Dominion					$ 700,000			$ 700,000		$ 0
[1]	Included within other current assets in the Consolidated Balance Sheets.
[2]	Includes $5.8 million and $14.2 million of capitalized expenditures for the three and nine months ended September 30, 2016, and $3.4 million and $8.9 million for the three and nine months ended September 30, 2015, respectively.

Income Taxes (Details)

Income Taxes (Details)		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
United States statutory rate		35.00%	35.00%
Partnership income not subject to income taxes	[1]	(35.00%)	(33.60%)
Increases resulting from:
State taxes, net of federal benefit	[2]	0.00%	0.10%
Effective tax rate		0.00%	1.50%
[1]	Reflects the pass-through entity status of Dominion Midstream, including the operations of DCG subsequent to the DCG Acquisition, and Cove Point.
[2]	2015 amounts are attributable to the operations of DCG prior to the DCG Acquisition.

Operating Segment (Details)

Operating Segment (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Operating revenue	[1]	$ 85	$ 103.1	$ 253.6	$ 286.9
Earnings from equity method investee		4.7	0	14.8	0
Net income (loss) including noncontrolling interest and DCG Predecessor		53.4	48.8	158.3	138.8
Net income (loss) including noncontrolling interest		53.4	48.8	158.3	136.5
Net income attributable to partners		24.3	18	69.9	47.4
Operating Segments | Dominion Energy
Segment Reporting Information [Line Items]
Operating revenue		85	103.1	253.6	286.9
Earnings from equity method investee		4.7		14.8
Net income (loss) including noncontrolling interest and DCG Predecessor		53.7	48.8	158.7	140.5
Net income (loss) including noncontrolling interest					137.2
Net income attributable to partners		24.6	18	70.3	48.1
Operating Segments | Corporate and Other
Segment Reporting Information [Line Items]
Operating revenue		0	0	0	0
Earnings from equity method investee		0		0
Net income (loss) including noncontrolling interest and DCG Predecessor		(0.3)	0	(0.4)	(1.7)
Net income (loss) including noncontrolling interest					(0.7)
Net income attributable to partners		$ (0.3)	$ 0	$ (0.4)	$ (0.7)
[1]	See Note 14 for amounts attributable to related parties.