Dominion Energy Midstream Partners 10-Q 5 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	Apr. 30, 2015
Document and Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	DM
Entity Registrant Name	Dominion Midstream Partners, LP
Entity Central Index Key	1603286
Current Fiscal Year End Date	-19
Entity Filer Category	Non-accelerated Filer
Entity Common Units Outstanding
Document and Entity Information [Line Items]
Entity Units Outstanding		37,092,305
Entity Subordinated Units Outstanding
Document and Entity Information [Line Items]
Entity Units Outstanding		31,972,789

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Operating revenue	$67.20	[1]
Operating Expenses
Purchased gas	3.9	[1]
Other operations and maintenance:
Affiliated suppliers	2.3
Other	6.2
Depreciation and amortization	9.3
Other taxes	5.1
Total operating expenses	26.8
Income from operations	40.4
Other income	0.1
Income from operations including noncontrolling interest before income taxes	40.5
Income tax expense	0
Net Income including noncontrolling interest	40.5
Less: Net income attributable to noncontrolling interest	28.7
Net income attributable to partners' ownership interest
Net income attributable to limited partners	11.8
Net income per unit (basic and diluted)
Net income per unit (basic and diluted)	$0.19
Common Units
Net income attributable to partners' ownership interest
Net income attributable to limited partners	5.9
Net income per unit (basic and diluted)
Net income per unit (basic and diluted)	$0.19
Subordinated Units
Net income attributable to partners' ownership interest
Net income attributable to limited partners	5.9
Net income per unit (basic and diluted)
Net income per unit (basic and diluted)	$0.19
Predecessor
Operating revenue			68.9	[1]
Operating Expenses
Purchased gas			5.3	[1]
Other operations and maintenance:
Affiliated suppliers			2
Other			8.4
Depreciation and amortization			7.8
Other taxes			5.6
Total operating expenses			29.1
Income from operations			39.8
Other income			0
Income from operations including noncontrolling interest before income taxes			39.8
Income tax expense			15.2
Net Income including noncontrolling interest			$24.60
[1]	See Note 10 for amounts attributable to related parties.

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 31, 2015		Dec. 31, 2014
In Millions, unless otherwise specified
Current Assets
Cash and cash equivalents	$38.80		$175.40
Customer receivables	22.7		19.9
Affiliated receivables	6.1		6.1
Prepayments	5.9		9.5
Materials and supplies	9		8.7
Regulatory assets	3.2		1.7
Other	2.9		4.7
Total current assets	88.6		226
Property, Plant and Equipment
Property, plant and equipment	2,471.30		2,203.10
Accumulated depreciation and amortization	-230.8		-231.2
Total property, plant and equipment, net	2,240.50		1,971.90
Deferred Charges and Other Assets
Goodwill	45.9		45.9
Intangible assets, net	12.1		12.1
Regulatory assets	2.6		2.5
Total deferred charges and other assets	60.6		60.5
Total assets	2,389.70		2,258.40
Current Liabilities
Accounts payable	103.3		3.3
Payables to affiliates	2.5		2.5
Accrued payroll and taxes	1.1		1.5
Regulatory liabilities	0.2		3.6
Deferred revenue	0.7		3.9
Natural gas imbalances	5.9	[1]	2.7	[1]
CPCN obligation	7.9		7.9
Other	8.8		6.4
Total current liabilities	130.4		31.8
Deferred Credits and Other Liabilities
Pension and other postretirement benefit liabilities	4.6	[1]	4.4	[1]
Regulatory liabilities	34.6		33.5
CPCN obligation	36.2		36.2
Other	1.5		1.7
Total deferred credits and other liabilities	76.9		75.8
Total liabilities	207.3		107.6
Commitments and Contingencies (see Note 8)
Equity and Partners' Capital
Total Dominion Midstream Partners, LP partners' capital	1,078.20		1,075.30
Noncontrolling interest	1,104.20		1,075.50
Total equity and partners' capital	2,182.40		2,150.80
Total liabilities and equity and partners' capital	2,389.70		2,258.40
Common Units
Equity and Partners' Capital
Common unitholders and Subordinated unitholder	396.3		395.4
Dominion
Equity and Partners' Capital
General Partner interest - Dominion (non-economic interest)	0		0
Dominion | Common Units
Equity and Partners' Capital
Common unitholders and Subordinated unitholder	214.2		213.7
Dominion | Subordinated Units
Equity and Partners' Capital
Common unitholders and Subordinated unitholder	$467.70		$466.20
[1]	See Note 10 for amounts attributable to related parties.

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical)	Mar. 31, 2015	Dec. 31, 2014
Common Units
Common unitholders and Subordinated unitholder - units issued	20,132,377	20,127,322
Common unitholders and Subordinated unitholder- units outstanding	20,132,377	20,127,322
Common Units | Dominion
Common unitholders and Subordinated unitholder - units issued	11,847,789	11,847,789
Common unitholders and Subordinated unitholder- units outstanding	11,847,789	11,847,789
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_Equi

Consolidated Statement of Equity and Partners' Capital (USD $)	Total	Common Unitholders and Subordinated Unitholder	Common Unitholders and Subordinated Unitholder	Common Unitholders and Subordinated Unitholder	General Partner Dominion (non-economic interest)	Total Dominion Midstream Partners, LP Partners' Equity and Capital	Noncontrolling interest
In Millions, unless otherwise specified		Common Units	Common Units	Subordinated Units	Dominion
		Members' Equity	Members' Equity	Members' Equity
			Dominion	Dominion
Balance at Dec. 31, 2014	$2,150.80	$395.40	$213.70	$466.20	$0	$1,075.30	$1,075.50
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	40.5	3.7	2.2	5.9	0	11.8	28.7
Distributions	-8.9	-2.8	-1.7	-4.4	0	-8.9	0
Balance at Mar. 31, 2015	$2,182.40	$396.30	$214.20	$467.70	$0	$1,078.20	$1,104.20

Statements_of_Cash_Flows

Statements of Cash Flows (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating Activities
Net income including noncontrolling interest	$40.50
Adjustments to reconcile net income including noncontrolling interest to net cash provided by operating activities:
Depreciation and amortization	9.3
Deferred income taxes	0
Changes in:
Customer receivables	-2.8
Affiliated receivables	0
Prepayments	3.6
Accounts payable	-0.5
Payables to affiliates	0
Accrued payroll and taxes	-0.4
Other operating assets and liabilities	-3.4
Net cash provided by operating activities	46.3
Investing Activities
Plant construction and other property additions	-173.7
Other	-0.3
Net cash used in investing activities	-174
Financing Activities
Contributions from Dominion	0
Net cash provided by (used in) financing activities	-8.9
Decrease in cash and cash equivalents	-136.6
Cash and cash equivalents at beginning of period	175.4
Cash and cash equivalents at end of period	38.8
Supplemental Cash Flow Information
Cash received for income taxes	0
Significant noncash investing and financing activities:
Accrued capital expenditures	103.2
Equity contribution from Dominion to relieve payables to affiliates
Significant noncash investing and financing activities:
Equity contribution from Dominion to relieve payables to affiliates	0
Common Units
Financing Activities
Distributions to unitholders	-2.8
Dominion | Common Units
Financing Activities
Distributions to unitholders	-1.7
Dominion | Subordinated Units
Financing Activities
Distributions to unitholders	-4.4
Predecessor
Operating Activities
Net income including noncontrolling interest		24.6
Adjustments to reconcile net income including noncontrolling interest to net cash provided by operating activities:
Depreciation and amortization		7.8
Deferred income taxes		5.1
Changes in:
Customer receivables		0
Affiliated receivables		-0.8
Prepayments		2.9
Accounts payable		-0.7
Payables to affiliates		2.5
Accrued payroll and taxes		10.9
Other operating assets and liabilities		-3.3
Net cash provided by operating activities		49
Investing Activities
Plant construction and other property additions		-76.2
Other		-0.1
Net cash used in investing activities		-76.3
Financing Activities
Contributions from Dominion		16.1
Net cash provided by (used in) financing activities		16.1
Decrease in cash and cash equivalents		-11.2
Cash and cash equivalents at beginning of period		11.2
Cash and cash equivalents at end of period		0
Supplemental Cash Flow Information
Cash received for income taxes		0.5
Significant noncash investing and financing activities:
Accrued capital expenditures		5.5
Predecessor | Equity contribution from Dominion to relieve payables to affiliates
Significant noncash investing and financing activities:
Equity contribution from Dominion to relieve payables to affiliates		20
Predecessor | Common Units
Financing Activities
Distributions to unitholders		0
Predecessor | Dominion | Common Units
Financing Activities
Distributions to unitholders		0
Predecessor | Dominion | Subordinated Units
Financing Activities
Distributions to unitholders		$0

Description_of_Business_and_Ba

Description of Business and Basis of Presentation	3 Months Ended
	Mar. 31, 2015
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 on March 11, 2014 by Dominion MLP Holding Company, LLC and Dominion Midstream GP, LLC, both indirect wholly-owned subsidiaries of Dominion, to acquire the Preferred Equity Interest and non-economic general partner interest in Cove Point from Dominion. Cove Point is the owner and operator of the Cove Point LNG Facility and the Cove Point Pipeline. On October 20, 2014, Dominion Midstream completed the Offering of 20,125,000 common units (including 2,625,000 common units issued pursuant to the exercise of the underwriters' over-allotment option) representing limited partner interests. A registration statement on Form S-1, as amended through the time of its effectiveness, was filed by Dominion Midstream with the SEC and was declared effective on October 10, 2014.
	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 will be made on a quarterly basis and will not be cumulative. The Preferred Equity Interest is also entitled to the Additional Return Distributions.
	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. Dominion Midstream owns the general partner interest and controls Cove Point 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.
	For the periods prior to the closing of the Offering on October 20, 2014, the financial statements included in this Quarterly Report on Form 10-Q were derived from the financial statements and accounting records of Cove Point as our predecessor. The financial statements were prepared using Dominion's historical basis in the assets and liabilities of Cove Point and include all revenues, costs, assets and liabilities attributed to Cove Point. For the period subsequent to the closing of the Offering, the Consolidated Financial Statements represent the consolidated results of operations, financial position and cash flows of Dominion Midstream.
	The financial statements for all periods presented include costs for certain general, administrative and corporate expenses assigned by DRS to Dominion Midstream and Cove Point on the basis of direct and allocated methods in accordance with Dominion Midstream's and Cove Point's services agreements with DRS. Where costs incurred cannot be determined by specific identification, the costs are allocated based on the proportional level of effort devoted by DRS 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 department. Management believes the assumptions and methodologies underlying the allocation of general corporate overhead expenses are reasonable. Nevertheless, the Consolidated Financial Statements prior to the Offering may not include all of the actual expenses that would have been incurred had we been a stand-alone publicly traded partnership during the periods presented, and may not reflect our actual results of operations, financial position and cash flows had we been a stand-alone publicly traded partnership during the periods prior to the Offering.

Acquisition

Acquisition	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Acquisition	Acquisition
	DCGT
	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 DCGT in exchange for total consideration of approximately $495.3 million, subject to working capital adjustments. Total consideration to Dominion consisted of the issuance of a two-year $295.3 million senior unsecured promissory note 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 amount of the promissory note is subject to change to correspond with any working capital adjustments. 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. DCGT owns and operates nearly 1,500 miles of FERC-regulated interstate natural gas pipeline in South Carolina and southeastern Georgia. This acquisition supports the expansion of Dominion Midstream's portfolio of natural gas terminaling, processing, storage, transportation and related assets.
	The sale of DCGT from Dominion to Dominion Midstream is considered to be a reorganization of entities under common control. As a result, Dominion Midstream's basis will be equal to Dominion's cost basis in the assets and liabilities of DCGT. Subsequent to the transaction, Dominion Midstream owns 100% of the membership interests in DCGT and will therefore consolidate DCGT.
	In connection with Dominion Midstream's acquisition of DCGT, 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.
	In connection with Dominion’s acquisition of DCGT on January 31, 2015, Dominion agreed to a rate moratorium which precludes DCGT from filing a Section 4 NGA general rate case to establish base rates that would be effective prior to January 1, 2018. In addition, DCGT entered into the following agreements with certain Dominion subsidiaries:
	•	DCGT entered into a services agreement with DRS. DRS provides administrative, management and other services to Dominion and its subsidiaries as a subsidiary service company.
	•	DCGT entered into a services agreement with Dominion Payroll Company, Inc. Dominion Payroll Company, Inc. provides human resources and operations services to Dominion and its subsidiaries as a subsidiary service company.

Significant_Accounting_Policie

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies
	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, 2014.
	In the opinion of management, the accompanying unaudited Consolidated Financial Statements contain all adjustments necessary to present fairly Dominion Midstream's financial position as of March 31, 2015, and its results of operations, cash flows and changes in equity for the three months ended March 31, 2015 and 2014. 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.

Net_Income_Per_Unit

Net Income Per Unit	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Net Income Per Unit	Net Income Per Unit
	Net income per 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 percentages, 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 unit.
	Net income per unit is only calculated for the periods subsequent to the Offering as no units were outstanding prior to October 20, 2014. Diluted net income per unit is the same as basic net income per unit as there were no potentially dilutive common or subordinated units outstanding as of March 31, 2015.
	The calculation of earnings per unit is as follows:
	Three Months Ended March 31,	2015
	(millions)
	Net income attributable to limited partners	$	11.8
	Less distributions declared on(1):
	Incentive distribution holder rights(2)	—
	Common unitholders	5.6
	Subordinated unitholder	5.6
	Total distributions declared	11.2
	Undistributed earnings	$	0.6
	-1	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 month period ending March 31, 2015. This distribution will be paid on May 15, 2015 to unitholders of record on May 5, 2015. The amount of distributions declared shown above is based on the units outstanding at March 31, 2015, and therefore excludes $0.9 million of distributions that will be paid on 5,112,139 common units issued to Dominion on April 1, 2015, in connection with the acquisition of DCGT. See Note 2 for further information.
	-2	Dominion is a non-economic general partner that holds all of the IDRs.
	Basic and diluted net income per unit
		Common Units		Subordinated Units		Total
	(millions, except for weighted average units and per unit data)
	Distributions declared	$	5.6	$	5.6	$	11.2
	Undistributed earnings	0.3		0.3		0.6
	Net income attributable to limited partners	$	5.9	$	5.9	$	11.8
	Weighted average units outstanding	31,980,110		31,972,789		63,952,899
	Net income per unit	$	0.19	$	0.19	$	0.19

Operating_Revenue

Operating Revenue	3 Months Ended
	Mar. 31, 2015
Revenue Recognition [Abstract]
Operating Revenue	Operating Revenue
	Dominion Midstream's operating revenue consists of the following:
		Three Months Ended March 31,
		2015		2014
	(millions)
	Gas transportation and storage	$	63.9	$	65.6
	Other	3.3		3.3
	Total operating revenue	$	67.2	$	68.9

Regulatory_Assets_and_Liabilit

Regulatory Assets and Liabilities	3 Months Ended
	Mar. 31, 2015
Regulated Operations [Abstract]
Regulatory Assets and Liabilities	Regulatory Assets and Liabilities
	Regulatory assets and liabilities include the following:
		31-Mar-15		31-Dec-14
	(millions)
	Regulatory assets:
	Unrecovered gas costs(1)	$	3	$	1.5
	Other	0.2		0.2
	Regulatory assets-current	3.2		1.7
	Income taxes recoverable through future rates(2)	2.6		2.5
	Regulatory assets-non-current	2.6		2.5
	Total regulatory assets	$	5.8	$	4.2
	Regulatory liabilities:
	Overrecovered gas costs(1)	$	—	$	0.5
	LNG cargo obligations(3)	—		3
	Other	0.2		0.1
	Regulatory liabilities-current	0.2		3.6
	Provision for future cost of removal(4)	33.9		33
	Other	0.7		0.5
	Regulatory liabilities-non-current	34.6		33.5
	Total regulatory liabilities	$	34.8	$	37.1
	-1	Reflects unrecovered/overrecovered gas costs at Cove Point, which are subject to annual filings with the 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 9 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2014 for further information.
	-4	Rates charged to customers by Cove Point include a provision for the cost of future activities to remove assets that are expected to be incurred at the time of retirement.
	At March 31, 2015, approximately $3.2 million of regulatory assets represented past expenditures on which Cove Point does not currently earn a return. These expenditures are expected to be recovered within one year.

Regulatory_Matters

Regulatory Matters	3 Months Ended
	Mar. 31, 2015
Regulated Operations [Abstract]
Regulatory Matters	Regulatory Matters
	The 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, the FERC has authority over rates, terms and conditions of services performed by Cove Point. The FERC also has jurisdiction over siting, construction and operation of natural gas import facilities and interstate natural gas pipeline facilities.
	There have been no significant developments regarding the regulatory matters disclosed in Note 9 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2014.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
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 the 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.
	Decommissioning Costs
	Under the terms of the 2005 Agreement, Cove Point would be responsible for certain onshore and offshore site restoration activities at the Cove Point site only if it voluntarily tenders title according to the terms of this agreement. As Cove Point is permitted to operate the Cove Point LNG Facility for an indefinite time period and currently has no plans to voluntarily tender title, Cove Point does not have sufficient information to determine a reasonable range of settlement dates for decommissioning and therefore has not recorded a liability.
	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 March 31, 2015, Cove Point had purchased $10.8 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.

Credit_Risk

Credit Risk	3 Months Ended
	Mar. 31, 2015
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.
	Cove Point provides service to approximately twenty customers, including the Storage Customers, marketers or end users and the Import Shippers. The three largest customers comprised approximately 94% of the total transportation and storage revenues for each of the three months ended March 31, 2015 and 2014, with Cove Point's largest customer representing approximately 73% of such amounts in each period. Cove Point has not experienced any credit losses in connection with its trade receivables. The majority of services are provided under long-term contracts at FERC-approved rates.

Related_Party_Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2015
Related Party Transactions [Abstract]
Related Party Transactions	Related-Party Transactions
	Dominion Midstream engages in related-party transactions primarily with other Dominion subsidiaries (affiliates). 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 10 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2014. At March 31, 2015 and December 31, 2014, amounts due to Dominion associated with these benefit plans were $4.6 million and $4.4 million, respectively, recorded in pension and other postretirement benefit liabilities in the Consolidated Balance Sheets. Dominion Midstream's acquisition of DCGT from Dominion and the related agreements entered into at that time are described in Note 2. A discussion of the significant related party transactions follows.
	Transactions with Affiliates
	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.
	In addition, Cove Point provides transportation services to affiliates and affiliates provide goods and services to Cove Point. The affiliated transactions are presented below:
		Three Months Ended March 31,
		2015		2014
	(millions)
	Sales of natural gas transportation services to affiliates	$	0.7	$	0.8
	Purchased gas from affiliates	0.2		0.2
	Services provided by DRS(1)(2)	3.3		3.3
	Goods and services provided by affiliates to Cove Point(1)	1		0.7
	-1	Includes $2.0 million of capitalized expenditures for each of the three months in 2015 and 2014.
	-2	Dominion Midstream determined that neither it nor Cove Point is the most closely associated entity with DRS, an affiliated variable interest entity, and therefore neither is the primary beneficiary. DRS provides accounting, legal, finance and certain administrative and technical services to all Dominion subsidiaries, including Dominion Midstream and Cove Point. Neither Dominion Midstream nor Cove Point has an obligation to absorb more than its allocated share of DRS costs.
	Advance from Affiliate
	An outstanding advance of $20.0 million previously received by Cove Point from an affiliate was converted to an equity contribution in March 2014.
	Dominion Credit Facility
	In connection with the Offering, Dominion Midstream entered into a credit facility with Dominion with a borrowing capacity of $300 million. The facility was undrawn at March 31, 2015. A summary of certain key terms of the credit facility with Dominion is included in Note 14 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2014.
	Income Taxes
	Prior to the Offering, Cove Point participated in Dominion's intercompany tax sharing agreement as described in Note 15 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2014. Cove Point's participation in this tax sharing agreement was terminated in 2014 in connection with the Offering.
	At the time of the Offering, Cove Point settled net income taxes payable and deferred income taxes to Dominion of $147.9 million through equity contributions from Dominion. Prior to the Offering, Cove Point settled net income taxes payable to Dominion of $1.2 million through equity contributions from Dominion during the year ended December 31, 2014.
	Natural Gas Imbalances
	Cove Point maintains natural gas imbalances with affiliates. The imbalances with affiliates are provided below:
		31-Mar-15		31-Dec-14
	(millions)
	Imbalances payable to affiliates	$	5.8	$	2.5
	Right of First Offer
	In connection with the Offering, we entered into a right of first offer agreement with Dominion as described in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2014. There have been no changes to this agreement.
	Contributions from Dominion
	In April 2015, Dominion contributed $205.2 million to Cove Point to fund capital expenditures related to the Liquefaction Project.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	Dominion Midstream is organized as an MLP, a pass-through entity for U.S. 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 U.S. federal and state income tax purposes. Accordingly, for the quarter ended March 31, 2015, Dominion Midstream’s Consolidated Financial Statements do not include income taxes.
	Prior to the completion of the Offering, Cove Point was not treated as a partnership for U.S. federal and state income tax purposes. Its business activities were included in the consolidated U.S. federal and certain state income tax returns of Dominion or DCPI. Cove Point’s current income taxes 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.
	For the three months ended March 31, 2014, the statutory U.S. federal income tax rate reconciles to the effective income tax rate as follows:
	Three Months Ended March 31,	2014
	U.S. statutory rate	35	%
	Increases resulting from:
	State taxes, net of federal benefit	3.2
	Effective tax rate	38.2	%
	See Note 15 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2014 for additional information.

Operating_Segment

Operating Segment	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Operating Segment	Operating Segment
	Dominion Midstream is organized primarily on the basis of products and services sold in the U.S. Dominion Energy, Dominion Midstream's operating segment, consists of natural gas transportation, storage and regasification services.
	Dominion Midstream also reports a Corporate and Other segment. The Corporate and Other segment primarily includes specific 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. There were no such items in the three months ended March 31, 2015 and 2014.
	The following table presents segment information pertaining to Dominion Midstream's operations:
		Dominion Energy		Corporate and		Total
				Other
	(millions)
	Three Months Ended March 31, 2015
	Operating revenue	$	67.2	$	—	$	67.2
	Net income including noncontrolling interest	40.5		—		40.5
	Net income attributable to limited partners	11.8		—		11.8
	Three Months Ended March 31, 2014
	Operating revenue	$	68.9	$	—	$	68.9
	Net income including noncontrolling interest	24.6		—		24.6

Significant_Accounting_Policie1

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
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. Dominion Midstream owns the general partner interest and controls Cove Point 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.
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, 2014.
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_Unit_Tables

Net Income Per Unit (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Schedule of Calculation of Earnings per Unit	The calculation of earnings per unit is as follows:
	Three Months Ended March 31,	2015
	(millions)
	Net income attributable to limited partners	$	11.8
	Less distributions declared on(1):
	Incentive distribution holder rights(2)	—
	Common unitholders	5.6
	Subordinated unitholder	5.6
	Total distributions declared	11.2
	Undistributed earnings	$	0.6
	-1	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 month period ending March 31, 2015. This distribution will be paid on May 15, 2015 to unitholders of record on May 5, 2015. The amount of distributions declared shown above is based on the units outstanding at March 31, 2015, and therefore excludes $0.9 million of distributions that will be paid on 5,112,139 common units issued to Dominion on April 1, 2015, in connection with the acquisition of DCGT. See Note 2 for further information.
	-2	Dominion is a non-economic general partner that holds all of the IDRs.
	Basic and diluted net income per unit
		Common Units		Subordinated Units		Total
	(millions, except for weighted average units and per unit data)
	Distributions declared	$	5.6	$	5.6	$	11.2
	Undistributed earnings	0.3		0.3		0.6
	Net income attributable to limited partners	$	5.9	$	5.9	$	11.8
	Weighted average units outstanding	31,980,110		31,972,789		63,952,899
	Net income per unit	$	0.19	$	0.19	$	0.19

Operating_Revenue_Tables

Operating Revenue (Tables)	3 Months Ended
	Mar. 31, 2015
Revenue Recognition [Abstract]
Operating Revenue	Dominion Midstream's operating revenue consists of the following:
		Three Months Ended March 31,
		2015		2014
	(millions)
	Gas transportation and storage	$	63.9	$	65.6
	Other	3.3		3.3
	Total operating revenue	$	67.2	$	68.9

Regulatory_Assets_and_Liabilit1

Regulatory Assets and Liabilities (Tables)	3 Months Ended
	Mar. 31, 2015
Regulated Operations [Abstract]
Schedule of Regulatory Assets	Regulatory assets and liabilities include the following:
		31-Mar-15		31-Dec-14
	(millions)
	Regulatory assets:
	Unrecovered gas costs(1)	$	3	$	1.5
	Other	0.2		0.2
	Regulatory assets-current	3.2		1.7
	Income taxes recoverable through future rates(2)	2.6		2.5
	Regulatory assets-non-current	2.6		2.5
	Total regulatory assets	$	5.8	$	4.2
	Regulatory liabilities:
	Overrecovered gas costs(1)	$	—	$	0.5
	LNG cargo obligations(3)	—		3
	Other	0.2		0.1
	Regulatory liabilities-current	0.2		3.6
	Provision for future cost of removal(4)	33.9		33
	Other	0.7		0.5
	Regulatory liabilities-non-current	34.6		33.5
	Total regulatory liabilities	$	34.8	$	37.1
	-1	Reflects unrecovered/overrecovered gas costs at Cove Point, which are subject to annual filings with the 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 9 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2014 for further information.
	-4	Rates charged to customers by Cove Point 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:
		31-Mar-15		31-Dec-14
	(millions)
	Regulatory assets:
	Unrecovered gas costs(1)	$	3	$	1.5
	Other	0.2		0.2
	Regulatory assets-current	3.2		1.7
	Income taxes recoverable through future rates(2)	2.6		2.5
	Regulatory assets-non-current	2.6		2.5
	Total regulatory assets	$	5.8	$	4.2
	Regulatory liabilities:
	Overrecovered gas costs(1)	$	—	$	0.5
	LNG cargo obligations(3)	—		3
	Other	0.2		0.1
	Regulatory liabilities-current	0.2		3.6
	Provision for future cost of removal(4)	33.9		33
	Other	0.7		0.5
	Regulatory liabilities-non-current	34.6		33.5
	Total regulatory liabilities	$	34.8	$	37.1
	-1	Reflects unrecovered/overrecovered gas costs at Cove Point, which are subject to annual filings with the 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 9 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2014 for further information.
	-4	Rates charged to customers by Cove Point 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)	3 Months Ended
	Mar. 31, 2015
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	The imbalances with affiliates are provided below:
		31-Mar-15		31-Dec-14
	(millions)
	Imbalances payable to affiliates	$	5.8	$	2.5
	The affiliated transactions are presented below:
		Three Months Ended March 31,
		2015		2014
	(millions)
	Sales of natural gas transportation services to affiliates	$	0.7	$	0.8
	Purchased gas from affiliates	0.2		0.2
	Services provided by DRS(1)(2)	3.3		3.3
	Goods and services provided by affiliates to Cove Point(1)	1		0.7
	-1	Includes $2.0 million of capitalized expenditures for each of the three months in 2015 and 2014.
	-2	Dominion Midstream determined that neither it nor Cove Point is the most closely associated entity with DRS, an affiliated variable interest entity, and therefore neither is the primary beneficiary. DRS provides accounting, legal, finance and certain administrative and technical services to all Dominion subsidiaries, including Dominion Midstream and Cove Point. Neither Dominion Midstream nor Cove Point has an obligation to absorb more than its allocated share of DRS costs.

Income_Taxes_Tables

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	For the three months ended March 31, 2014, the statutory U.S. federal income tax rate reconciles to the effective income tax rate as follows:
	Three Months Ended March 31,	2014
	U.S. statutory rate	35	%
	Increases resulting from:
	State taxes, net of federal benefit	3.2
	Effective tax rate	38.2	%

Operating_Segment_Tables

Operating Segment (Tables)	3 Months Ended
	Mar. 31, 2015
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		Total
				Other
	(millions)
	Three Months Ended March 31, 2015
	Operating revenue	$	67.2	$	—	$	67.2
	Net income including noncontrolling interest	40.5		—		40.5
	Net income attributable to limited partners	11.8		—		11.8
	Three Months Ended March 31, 2014
	Operating revenue	$	68.9	$	—	$	68.9
	Net income including noncontrolling interest	24.6		—		24.6

Description_of_Business_and_Ba1

Description of Business and Basis of Presentation (Details) (Common Units)	0 Months Ended
	Oct. 20, 2014
IPO
Subsidiary, Sale of Stock [Line Items]
Number of units issued	20,125,000
Over-Allotment Option
Subsidiary, Sale of Stock [Line Items]
Number of units issued	2,625,000

Acquisition_Details

Acquisition (Details) (Subsequent Event, DCGT, Affiliates, USD $)	0 Months Ended
In Millions, except Share data, unless otherwise specified	Apr. 01, 2015
Partnership Interest
Business Acquisition [Line Items]
Number of common units issued	5,112,139
Dominion
Business Acquisition [Line Items]
Total consideration	495.3
Length of FERC regulated interstate natural gas pipeline	1,500
Dominion | Partnership Interest
Business Acquisition [Line Items]
Number of common units issued	5,112,139
Value of common units issued	200
Number of trading days	10 days
Price per unit	39.12
Dominion | Membership Interest
Business Acquisition [Line Items]
Ownership percentage of membership interests in DCGT	100.00%
Dominion | Notes Payable
Business Acquisition [Line Items]
Term of senior unsecured promissory note payable	2 years
Senior unsecured promissory note payable	295.3
Annual interest rate (percentage)	0.60%

Net_Income_Per_Unit_Details

Net Income Per Unit (Details) (USD $)	3 Months Ended		0 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2015		Apr. 22, 2015	Apr. 01, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to limited partners	$11.80
Incentive distribution holder rights	0	[1],[2]
Total distributions declared	11.2
Undistributed earnings	0.6
Weighted average units outstanding	63,952,899
Net income per unit (basic and diluted)	$0.19
Subsequent Event
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Distribution declared on Common and Subordinated unitholders			12.1
Quarterly distribution per unit			$0.18
Subsequent Event | DCGT | Affiliates | Partnership Interest
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Distribution declared on Common and Subordinated unitholders				0.9
Number of common units issued				5,112,139
Common Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to limited partners	5.9
Distribution declared on Common and Subordinated unitholders	5.6	[1]
Total distributions declared	5.6
Undistributed earnings	0.3
Weighted average units outstanding	31,980,110
Net income per unit (basic and diluted)	$0.19
Subordinated Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to limited partners	5.9
Distribution declared on Common and Subordinated unitholders	5.6	[1]
Total distributions declared	5.6
Undistributed earnings	$0.30
Weighted average units outstanding	31,972,789
Net income per unit (basic and diluted)	$0.19
[1]	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 month period ending March 31, 2015. This distribution will be paid on May 15, 2015 to unitholders of record on May 5, 2015. The amount of distributions declared shown above is based on the units outstanding at March 31, 2015, and therefore excludes $0.9 million of distributions that will be paid on 5,112,139 common units issued to Dominion on April 1, 2015, in connection with the acquisition of DCGT. See Note 2 for further information.
[2]	Dominion is a non-economic general partner that holds all of the IDRs.

Operating_Revenue_Details

Operating Revenue (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Public Utilities, General Disclosures [Line Items]
Gas transportation and storage	$63.90
Other	3.3
Total operating revenue	67.2	[1]
Predecessor
Public Utilities, General Disclosures [Line Items]
Gas transportation and storage			65.6
Other			3.3
Total operating revenue			$68.90	[1]
[1]	See Note 10 for amounts attributable to related parties.

Regulatory_Assets_and_Liabilit2

Regulatory Assets and Liabilities (Regulatory Assets) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Regulatory Assets [Line Items]
Regulatory assets-current	$3.20		$1.70
Regulatory assets-non-current	2.6		2.5
Total regulatory assets	5.8		4.2
Past expenditures in which no return is expected	3.2
Recovery period of expenditures	1 year
Unrecovered gas costs
Regulatory Assets [Line Items]
Regulatory assets-current	3	[1]	1.5	[1]
Other
Regulatory Assets [Line Items]
Regulatory assets-current	0.2		0.2
Income taxes recoverable through future rates
Regulatory Assets [Line Items]
Regulatory assets-non-current	$2.60	[2]	$2.50	[2]
[1]	Reflects unrecovered/overrecovered gas costs at Cove Point, which are subject to annual filings with the 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_Liabilit3

Regulatory Assets and Liabilities (Regulatory Liabilities) (Details) (USD $)	Mar. 31, 2015		Dec. 31, 2014
In Millions, unless otherwise specified
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	$0.20		$3.60
Regulatory liabilities-non-current	34.6		33.5
Total regulatory liabilities	34.8		37.1
Overrecovered gas costs
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	0	[1]	0.5	[1]
LNG cargo obligations
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	0	[2]	3	[2]
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	0.2		0.1
Regulatory liabilities-non-current	0.7		0.5
Provision for future cost of removal
Regulatory Liabilities [Line Items]
Regulatory liabilities-non-current	$33.90	[3]	$33	[3]
[1]	Reflects unrecovered/overrecovered gas costs at Cove Point, which are subject to annual filings with the FERC.
[2]	Reflects obligations to the Import Shippers for LNG cargo received. See Note 9 to the Consolidated Financial Statements in Dominion Midstream's Annual Report on Form 10-K for the year ended December 31, 2014 for further information.
[3]	Rates charged to customers by Cove Point include a provision for the cost of future activities to remove assets that are expected to be incurred at the time of retirement.

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	Mar. 31, 2015
Surety Bond
Other Commitments [Line Items]
Total amount of commitment	$10,800,000
Annual Contributions to Cove Point Natural Heritage Trust
Other Commitments [Line Items]
Total amount of commitment	300,000
Annual Contributions to Cove Point Natural Heritage Trust | Minimum
Other Commitments [Line Items]
Total amount of commitment	$0

Credit_Risk_Details

Credit Risk (Details) (Customer Concentration Risk, Sales Revenue, Net)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
	customer	customer
Concentration Risk [Line Items]
Number of customers	20
Three Largest Customers
Concentration Risk [Line Items]
Number of customers	3
Percentage of total transportation and storage revenues	94.00%
Largest Customer
Concentration Risk [Line Items]
Percentage of total transportation and storage revenues	73.00%
Predecessor | Three Largest Customers
Concentration Risk [Line Items]
Number of customers		3
Percentage of total transportation and storage revenues		94.00%
Predecessor | Largest Customer
Concentration Risk [Line Items]
Percentage of total transportation and storage revenues		73.00%

Related_Party_Transactions_Det

Related Party Transactions (Details) (USD $)	3 Months Ended				0 Months Ended	10 Months Ended	1 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Oct. 20, 2014	Oct. 19, 2014	Apr. 30, 2015	Dec. 31, 2014		Dec. 31, 2013
Related Party Transaction [Line Items]
Imbalances payable to affiliates	$5,900,000	[1]						$2,700,000	[1]
Affiliates
Related Party Transaction [Line Items]
Sales of natural gas transportation services to affiliates	700,000
Capital expenditures	2,000,000
Imbalances payable to affiliates	5,800,000							2,500,000
Affiliates | Pension and Other Postretirement Benefit Liabilities
Related Party Transaction [Line Items]
Amounts due to Dominion associated with benefit plans	4,600,000							4,400,000
Affiliates | Predecessor
Related Party Transaction [Line Items]
Sales of natural gas transportation services to affiliates			800,000
Capital expenditures			2,000,000
Affiliates | Predecessor | Payables to Affiliates
Related Party Transaction [Line Items]
Advance from affiliate										20,000,000
Affiliates | Purchased gas from affiliates
Related Party Transaction [Line Items]
Purchased gas from affiliates	200,000
Affiliates | Purchased gas from affiliates | Predecessor
Related Party Transaction [Line Items]
Purchased gas from affiliates			200,000
Affiliates | Services provided by DRS
Related Party Transaction [Line Items]
Goods and services provided by affiliates	3,300,000	[2],[3]
Affiliates | Services provided by DRS | Predecessor
Related Party Transaction [Line Items]
Goods and services provided by affiliates			3,300,000	[2],[3]
Affiliates | Goods and services provided by affiliates to Cove Point
Related Party Transaction [Line Items]
Goods and services provided by affiliates	1,000,000	[2]
Affiliates | Goods and services provided by affiliates to Cove Point | Predecessor
Related Party Transaction [Line Items]
Goods and services provided by affiliates			700,000	[2]
Affiliates | Credit Facility with Dominion | IPO | Line of Credit
Related Party Transaction [Line Items]
Borrowing capacity					300,000,000
Affiliates | Tax Sharing Agreement | Equity contribution from Dominion related to income taxes
Related Party Transaction [Line Items]
Equity contribution from Dominion					147,900,000
Affiliates | Tax Sharing Agreement | Predecessor | Equity contribution from Dominion related to income taxes
Related Party Transaction [Line Items]
Equity contribution from Dominion						1,200,000
Affiliates | Capital Expenditures related to Liquefaction Project | Subsequent Event
Related Party Transaction [Line Items]
Contributions from Dominion							$205,200,000
[1]	See Note 10 for amounts attributable to related parties.
[2]	Dominion Midstream determined that neither it nor Cove Point is the most closely associated entity with DRS, an affiliated variable interest entity, and therefore neither is the primary beneficiary. DRS provides accounting, legal, finance and certain administrative and technical services to all Dominion subsidiaries, including Dominion Midstream and Cove Point. Neither Dominion Midstream nor Cove Point has an obligation to absorb more than its allocated share of DRS costs.
[3]	Includes $2.0 million of capitalized expenditures for each of the three months in 2015 and 2014.

Income_Taxes_Details

Income Taxes (Details) (Predecessor)	3 Months Ended
	Mar. 31, 2014
Predecessor
Income Taxes [Line Items]
U.S. statutory rate	35.00%
Increases resulting from:
State taxes, net of federal benefit	3.20%
Effective tax rate	38.20%

Operating_Segment_Narrative_De

Operating Segment (Narrative) (Details) (Corporate and Other, USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Specific items attributable to operating segment that are not included in profit measures	$0
Predecessor
Segment Reporting Information [Line Items]
Specific items attributable to operating segment that are not included in profit measures		$0

Operating_Segment_Schedule_of_

Operating Segment (Schedule of Segment Reporting Information, by Segment) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Segment Reporting Information [Line Items]
Operating revenue	$67.20	[1]
Net income including noncontrolling interest	40.5
Net income attributable to limited partners	11.8
Predecessor
Segment Reporting Information [Line Items]
Operating revenue			68.9	[1]
Net income including noncontrolling interest			24.6
Dominion Energy
Segment Reporting Information [Line Items]
Operating revenue	67.2
Net income including noncontrolling interest	40.5
Net income attributable to limited partners	11.8
Dominion Energy | Predecessor
Segment Reporting Information [Line Items]
Operating revenue			68.9
Net income including noncontrolling interest			24.6
Corporate and Other
Segment Reporting Information [Line Items]
Operating revenue	0
Net income including noncontrolling interest	0
Net income attributable to limited partners	0
Corporate and Other | Predecessor
Segment Reporting Information [Line Items]
Operating revenue			0
Net income including noncontrolling interest			$0
[1]	See Note 10 for amounts attributable to related parties.