Questar Gas 10-Q 3 Aug 17 2017 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Jul. 14, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	QUESTAR GAS CO
Entity Central Index Key	68,589
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		9,189,626

Statements of Income

Statements of Income - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Operating Revenue	[1]	$ 139.7	$ 128.2	$ 536.6	$ 536.1
Operating Expenses
Cost of sales	[1]	75.5	67.8	316.8	324.7
Other operations and maintenance	[1]	44.6	36.3	86.3	83.9
Depreciation and amortization		16.5	15	32.7	29.7
Other taxes		5.6	5.3	11.4	10.6
Total Operating Expenses		142.2	124.4	447.2	448.9
Income (loss) from operations		(2.5)	3.8	89.4	87.2
Other income		1	0.9	2	1.9
Interest expense	[1]	8.5	7.5	17	15.2
Income (loss) from operations before income tax expense		(10)	(2.8)	74.4	73.9
Income tax expense (benefit)		(3.8)	(1.2)	28.4	27.9
Net Income (Loss)		$ (6.2)	$ (1.6)	$ 46	$ 46
[1]	See Note 12 for amounts attributable to related parties.

Balance Sheets

Balance Sheets - USD ($) $ in Millions		Jun. 30, 2017	Dec. 31, 2016	[1]
Current Assets
Cash and cash equivalents		$ 2.1	$ 7.6
Customer receivables (less allowance for doubtful accounts of $2.0 and $1.7 )		52.3	163.7
Receivable from affiliates		0.6	0.6
Inventories at lower of average cost or market:
Gas stored underground		21.8	49.3
Materials and supplies		25.7	27.6
Regulatory assets		13.4	9.6
Other		5	3.7
Total current assets		120.9	262.1
Property, Plant and Equipment
Property, plant and equipment		2,917.9	2,883
Accumulated depreciation and amortization		(727.6)	(737.6)
Total property, plant and equipment, net		2,190.3	2,145.4
Deferred Charges and Other Assets
Receivable from affiliates		98.6	87.8
Other noncurrent assets		12.1	11.2
Total deferred charges and other assets		110.7	99
Total assets		2,421.9	2,506.5
Current Liabilities
Securities due within one year		134.5	14.5
Short-term debt		135	200
Affiliated current borrowings		10	48
Accounts payable and accrued expenses		71.1	117.2
Accounts payable to affiliates		42.7	43.5
Customer advances		11.8	27.9
Regulatory liabilities		9.1	6.5
Other current liabilities		2.8	1.7
Total current liabilities		417	459.3
Long-Term Debt		496.5	616.3
Deferred Credits and Other Liabilities
Deferred income taxes		504.3	475.8
Regulatory liabilities		190.8	189.1
Payables to affiliates		12.8	13
Other noncurrent liabilities		96.9	95.4
Total deferred credits and other liabilities		804.8	773.3
Total liabilities		1,718.3	1,848.9
Commitments and Contingencies (see Note 9)
Equity
Common stock - par value $2.50	[2]	23	23
Additional paid-in capital		272.5	272.5
Retained earnings		408.1	362.1
Total common shareholder's equity		703.6	657.6
Total liabilities and shareholder's equity		$ 2,421.9	$ 2,506.5
[1]	Questar Gas' Balance Sheet at December 31, 2016 has been derived from the audited Balance Sheet at that date.
[2]	50.0 million shares authorized; 9.2 million shares outstanding at June 30, 2017 and December 31, 2016.

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Customer receivables, allowance for doubtful accounts	$ 2	$ 1.7
Common stock , par value (in dollars per share)	$ 2.50	$ 2.50
Common stock, authorized (in shares)	50,000,000	50,000,000
Common stock, outstanding (in shares)	9,200,000	9,200,000

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017		Jun. 30, 2016
Operating Activities
Net income	$ 46		$ 46
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	32.7		32.6
Deferred income taxes	28.5		12.5
Other adjustments for non-cash items	0.5		0.8
Changes in operating assets and liabilities	65		182.3
Net cash provided by operating activities	172.7		274.2
Investing Activities
Property, plant and equipment purchased	(75.4)		(124.3)
Cash used in disposition of assets	0		(1.2)
Other	0.2		0
Net cash used in investing activities	(75.2)		(125.5)
Financing Activities
Repayment of short-term debt, net	(65)		0
Repayment of affiliated current borrowings, net	(38)		(144.3)
Other	0		5.1
Net cash used in financing activities	(103)		(159.2)
Decrease in cash and cash equivalents	(5.5)		(10.5)
Cash and cash equivalents at beginning of year	7.6	[1]	10.5
Cash and cash equivalents at end of year	2.1		0
Significant noncash investing activities:
Accrued capital expenditures	18.8		22.6
Dominion Energy Questar
Financing Activities
Dividends paid to Dominion Energy Questar	$ 0		$ (20)
[1]	Questar Gas' Balance Sheet at December 31, 2016 has been derived from the audited Balance Sheet at that date.

Nature of Operations

Nature of Operations	6 Months Ended
	Jun. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Operations	Note 1. Nature of Operations Questar Gas is a wholly-owned subsidiary of Dominion Energy Questar which, effective September 2016, is a wholly-owned subsidiary of Dominion Energy. Questar Gas distributes natural gas as a public utility in Utah, southwestern Wyoming and a small portion of southeastern Idaho. The Utah, Wyoming and Idaho Commissions have granted Questar Gas the necessary regulatory approvals to serve these areas. Questar Gas also has long-term franchises granted by communities and counties within its service area. Revenue generated by Questar Gas is based primarily on rates established by the Utah and Wyoming Commissions. The Idaho Commission has contracted with the Utah Commission for rate oversight of Questar Gas operations in Idaho. Wexpro, an affiliate, provides the majority of Questar Gas' natural gas supply and Dominion Energy Questar Pipeline, an affiliate, provides the majority of Questar Gas' transportation and storage services.

Significant Accounting Policies

Significant Accounting Policies	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Significant Accounting Policies	Note 2. Significant Accounting Policies As permitted by the rules and regulations of the SEC, Questar Gas' accompanying unaudited Financial Statements contain certain condensed financial information and exclude certain footnote disclosures normally included in annual audited financial statements prepared in accordance with GAAP. These unaudited Financial Statements should be read in conjunction with the Financial Statements and Notes in Questar Gas' Annual Report on Form 10-K for the year ended December 31, 2016. In the opinion of management, the accompanying unaudited Financial Statements contain all adjustments necessary to present fairly its financial position as of June 30, 2017, its results of operations for the three and six months ended June 30, 2017 and 2016 and its cash flows for the six months ended June 30, 2017 and 2016. Such adjustments are normal and recurring in nature unless otherwise noted. Questar Gas makes certain estimates and assumptions in preparing its 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, expenses and cash flows 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. Questar Gas reports certain contracts and instruments at fair value. See Note 4 for further information on fair value measurements. Certain amounts in the 2016 Financial Statements and Notes have been reclassified to conform to the 2017 presentation for comparative purposes. The reclassifications did not affect Questar Gas' net income, total assets, liabilities, equity or cash flows.

Operating Revenue

Operating Revenue	6 Months Ended
	Jun. 30, 2017
Regulated And Unregulated Operating Revenue [Abstract]
Operating Revenue	Note 3. Operating Revenue Questar Gas' operating revenue consists of the following: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 (millions) Residential and commercial gas sales $ 122.0 $ 112.9 $ 500.5 $ 504.6 Industrial gas sales 3.1 4.5 6.3 9.5 Gas transportation 6.3 5.7 13.2 11.7 Other (1) 8.3 5.1 16.6 10.3 Total operating revenue $ 139.7 $ 128.2 $ 536.6 $ 536.1 (1) See Note 11 for amounts attributable to related parties.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 4. Fair Value Measurements Questar Gas' fair value measurements are made in accordance with the policies discussed in Note 5 to the Financial Statements in Questar Gas' Annual Report on Form 10-K for the year ended December 31, 2016. See Note 5 in this report for further information about Questar Gas' derivatives and hedge accounting activities. Questar Gas enters into certain physical forwards and options, which are considered Level 3 as they have one or more inputs that are not observable and are significant to the valuation. The discounted cash flow method is used to value Level 3 physical forward contracts. An option model is used to value Level 3 physical options. The discounted cash flow model for forwards calculates mark-to-market valuations based on forward market prices, original transaction prices, volumes, risk-free rate of return, and credit spreads. The option model calculates mark-to-market valuations using variations of the Black-Scholes option model. The inputs into the models are the forward market prices, implied price volatilities, risk-free rate of return, the option expiration dates, the option strike prices, the original sales prices, and volumes. The following table presents Questar Gas' quantitative information about Level 3 fair value measurements at June 30, 2017. The range and weighted average are presented in dollars for market price inputs and percentages for price volatility Fair Value (millions) Valuation Techniques Unobservable Input Range Weighted Average (1) Assets Physical options: Natural gas $ 0.3 Option model Market price (per Dth) (2 ) 3.2 - 3.4 3.3 Price volatility (3 ) 25.1% - 31.7% 27.7 % Total assets $ 0.3 Liabilities Physical forwards: Natural gas (4) $ 0.5 Discounted cash flow Market price (per Dth) (2 ) 2.3 - 3.4 2.9 Total liabilities $ 0.5 (1) Averages weighted by volume. (2 ) Represents market prices beyond defined terms for Level 1 and 2. (3 ) Represents volatilities unrepresented in published markets. (4 ) Includes basis. Sensitivity of the fair value measurements to changes in the significant unobservable inputs is as follows: Significant Unobservable Inputs Position Change to Input Impact on Fair Value Measurement Market price Buy Increase (decrease) Gain (loss) Market price Sell Increase (decrease) Loss (gain) Price volatility Buy Increase (decrease) Gain (loss) Price volatility Sell Increase (decrease) Loss (gain) Recurring Fair Value Measurements The following table presents Questar Gas’ assets and liabilities that are measured at fair value on a recurring basis for each hierarchy level, including both current and noncurrent portions. Level 1 Level 2 Level 3 Total (millions) At June 30, 2017 Assets: Derivatives: Commodity $ — $ — $ 0.3 $ 0.3 Total assets $ — $ — $ 0.3 $ 0.3 Liabilities: Derivatives: Commodity $ — $ 0.1 $ 0.5 $ 0.6 Total liabilities $ — $ 0.1 $ 0.5 $ 0.6 At December 31, 2016 Assets: Derivatives: Commodity $ — $ 0.1 $ — $ 0.1 Total assets $ — $ 0.1 $ — $ 0.1 Liabilities: Derivatives: Commodity $ — $ 0.1 $ — $ 0.1 Total liabilities $ — $ 0.1 $ — $ 0.1 The following table presents the net change in Questar Gas' assets and liabilities measured at fair value on a recurring basis and included in the Level 3 fair value category. Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 (millions) Beginning balance $ (1.3 ) $ — $ — $ — Total realized and unrealized gains (losses): Included in earnings (1) — — (0.1 ) — Included in regulatory assets/liabilities 1.0 — (0.3 ) — Settlements — — 0.1 — Purchases 0.1 — 0.1 — Ending balance $ (0.2 ) $ — $ (0.2 ) $ — (1) The gains and losses included in earnings were classified in cost of sales. There were no unrealized gains or losses included in earnings in the Level 3 fair value category relating to assets/liabilities still held at the reporting date for the three and six months ended June 30, 2017. Fair Value of Financial Instruments Substantially all of Questar Gas' financial instruments are recorded at fair value, with the exception of the instruments described below, which are reported at historical cost. Estimated fair values have been determined using available market information and valuation methodologies considered appropriate by management. The carrying amount of cash and cash equivalents, customer receivables, receivable from affiliates, short-term debt, affiliated current borrowings, accounts payable and accounts payable to affiliates are representative of fair value because of the short-term nature of these instruments. For Questar Gas' financial instruments that are not recorded at fair value, the carrying amounts and estimated fair values are as follows: June 30, 2017 December 31, 2016 Carrying Amount Estimated Fair Value (1) Carrying Amount Estimated Fair Value (1) (millions) Long-term debt, including securities due within one year (2) $ 631.0 $ 687.1 $ 630.8 $ 672.6 (1) Fair value is estimated using market prices, where available, and interest rates currently available for issuance of debt with similar terms and remaining maturities. The fair value measurements are classified as Level 2. (2) Carrying amount includes amounts which represent the unamortized debt issuance costs, discount or premium.

Derivatives and Hedge Accountin

Derivatives and Hedge Accounting Activities	6 Months Ended
	Jun. 30, 2017
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivatives and Hedge Accounting Activities	Note 5. Derivatives and Hedge Accounting Activities Questar Gas' accounting policies, objectives and strategies for using derivative instruments are discussed in Note 2 to the Financial Statements in the Questar Gas' Annual Report on Form 10-K for the year ended December 31, 2016. See Note 4 in this report for further information about fair value measurements and associated valuation methods for derivatives. Derivative assets and liabilities are presented gross on Questar Gas' Balance Sheets. Questar Gas' derivative contracts include over-the-counter transactions, which are bilateral contracts that are transacted directly with a counterparty. At June 30, 2017, substantially all of Questar Gas' derivative assets and liabilities were not subject to a master netting or similar arrangement. Volumes The following table presents the volume of Questar Gas' derivative activity at June 30, 2017. These volumes are based on open derivative positions and represent the combined absolute value of its long and short positions, except in the case of offsetting transactions, for which they represent the absolute value of the net volume of its long and short positions. Current Noncurrent Natural Gas (bcf): Basis 12.1 25.9 Fair Value and Gains and Losses on Derivative Instruments The following table presents the fair values of Questar Gas' derivatives and where they are presented in its Balance Sheets. Fair Value - Derivatives not under Hedge Accounting Total Fair Value (millions) At June 30, 2017 ASSETS Current Assets Commodity $ 0.3 $ 0.3 Total current derivative assets (1) 0.3 0.3 Total derivative assets $ 0.3 $ 0.3 LIABILITIES Current Liabilities Commodity $ 0.2 $ 0.2 Total current derivative liabilities (2) 0.2 0.2 Noncurrent Liabilities Commodity 0.4 0.4 Total noncurrent derivative liabilities (3) 0.4 0.4 Total derivative liabilities $ 0.6 $ 0.6 At December 31, 2016 ASSETS Current Assets Commodity $ 0.1 $ 0.1 Total current derivative assets (1) 0.1 0.1 Total derivative assets $ 0.1 $ 0.1 LIABILITIES Current Liabilities Commodity $ 0.1 $ 0.1 Total current derivative liabilities (2) 0.1 0.1 Total derivative liabilities $ 0.1 $ 0.1 (1) Current derivative assets are presented in other current assets in Questar Gas' Balance Sheets. (2) Current derivative liabilities are presented in other current liabilities in Questar Gas’ Balance Sheets. (3) Noncurrent derivative liabilities are presented in other noncurrent liabilities in Questar Gas' Balance Sheets. The following table presents the gains and losses on Questar Gas' derivatives, as well as where the associated activity is presented in its Statements of Income. Amount (1) Three Months Ended June 30, Six Months Ended June 30, Derivatives not designated as hedging instruments 2017 2016 2017 2016 (millions) Derivative Type and Location of Gains (Losses) Commodity (2) $ — $ — $ (0.5 ) $ — Total $ — $ — $ (0.5 ) $ — (1) Includes derivative activity amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/liabilities have no associated effect in Questar Gas' Statements of Income. (2) Amounts recorded in Questar Gas' Statements of Income are classified in cost of sales .

Regulatory Assets and Liabiliti

Regulatory Assets and Liabilities	6 Months Ended
	Jun. 30, 2017
Regulated Operations [Abstract]
Regulatory Assets and Liabilities	Note 6. Regulatory Assets and Liabilities Regulatory assets and liabilities include the following: June 30, December 31, 2017 2016 (millions) Regulatory assets: Purchased-gas adjustment (1) $ 10.8 $ 3.4 Contract withholding (2) — 2.6 Pipeline integrity costs (3) 1.9 1.9 Other 0.7 1.7 Regulatory assets-current 13.4 9.6 Cost of reacquired debt (4) 2.9 3.2 Pipeline integrity costs (3) 1.1 2.3 Other 0.4 — Regulatory assets-noncurrent (5) 4.4 5.5 Total regulatory assets $ 17.8 $ 15.1 Regulatory liabilities: Cost of plant removal and AROs (6) $ 5.0 $ 3.5 CET (7) 2.3 2.9 Curtailment penalty (8) 1.1 — Other 0.7 0.1 Regulatory liabilities-current 9.1 6.5 Cost of plant removal and AROs (6) 190.8 189.1 Regulatory liabilities-noncurrent 190.8 189.1 Total regulatory liabilities $ 199.9 $ 195.6 (1) Purchased-gas costs that are different from those provided for in present rates are accumulated and recovered or credited through future rate changes. ( 2 ) Represents a disputed amount withheld from a supplier of storage services. The dispute was settled in March 2017 and the amount reversed, which resulted in no material impact to Questar Gas' results of operations, financial position or cash flows. ( 3 ) The costs of complying with pipeline-integrity regulations are recovered in rates subject to a Utah Commission order. Questar Gas is allowed to recover $7.0 million per year. Costs incurred in excess of this amount will be recovered in future rate changes. ( 4 ) Gains and losses on the reacquisition of debt by rate-regulated companies are deferred and amortized as interest expense over the would-be remaining life of the reacquired debt. The reacquired debt costs had a weighted-average life of approximately 5.6 years as of June 30, 2017. ( 5 ) Noncurrent regulatory assets are presented in other noncurrent assets in the Balance Sheets. ( 6 ) Cost of plant removal and AROs represent amounts recovered from customers for costs of future activities to remove assets that are expected to be incurred at the time of retirement. ( 7 ) Represents the difference between actual and allowed revenues. Any deficiency in amounts collected is recovered through periodic rate adjustments. ( 8 ) Interruptible customers who fail to interrupt service when called upon by Questar Gas incur a curtailment penalty. Penalties recovered by Questar Gas are credited to ratepayers as a reduction to the infrastructure-replacement program.

Regulatory Matters

Regulatory Matters	6 Months Ended
	Jun. 30, 2017
Regulated Operations [Abstract]
Regulatory Matters	Note 7. Regulatory Matters As a public utility, Questar Gas is subject to the jurisdiction of the Utah Commission and the Wyoming Commission. Natural gas sales and transportation services are provided under rate schedules approved by the two regulatory commissions. There have been no significant developments regarding the pending regulatory matters disclosed in Note 10 to the Financial Statements in Questar Gas' Annual Report on Form 10-K for the year ended December 31, 2016.

Variable Interest Entity

Variable Interest Entity	6 Months Ended
	Jun. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Variable Interest Entity	Note 8. Variable Interest Entity The primary beneficiary of a VIE is required to consolidate the VIE and to disclose certain information about its significant variable interest in the VIE. The primary beneficiary of a VIE is the entity that has both: (1) the power to direct 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. Questar Gas purchased shared services from DEQPS of $0.3 million for the three months ended June 30, 2017 and $0.7 million for the six months ended June 30, 2017. DEQPS provides operational services to certain Dominion Energy subsidiaries, including Questar Gas, as a subsidiary service company. The Balance Sheet at June 30, 2017 included amounts due to DEQPS of $0.1 million. Questar Gas determined that it is not the primary beneficiary of DEQPS as it does not have 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 it. Questar Gas has no obligation to absorb more than its allocated share of DEQPS costs.

Significant Financing Transacti

Significant Financing Transactions	6 Months Ended
	Jun. 30, 2017
Short Term Debt Other Disclosures [Abstract]
Significant Financing Transactions	Note 9. Significant Financing Transactions Questar Gas uses short-term debt to fund working capital requirements and as a bridge to long-term debt financings. The levels of borrowing may vary significantly during the course of the year, depending upon the timing and amount of cash requirements not satisfied by cash from operations. Questar Gas’ short-term financing is supported by the two joint revolving credit facilities with Dominion Energy, Virginia Power and Dominion Energy Gas. These credit facilities can be used for working capital, as support for the combined commercial paper programs of Dominion Energy, Virginia Power, Dominion Energy Gas and Questar Gas and for other general corporate purposes. At June 30, 2017, Questar Gas' commercial paper and letters of credit outstanding under its joint credit facilities with Dominion Energy, Virginia Power and Dominion Energy Gas, were as follows: Facility Limit (1) Outstanding Commercial Paper Outstanding Letters of Credit (millions) Joint revolving credit facility (1) $ 500.0 $ 135.0 $ — Joint revolving credit facility (1) 500.0 — — Total $ 1,000.0 $ 135.0 $ — (1) A maximum of a combined $1.0 billion of the facilities is available to Questar Gas, assuming adequate capacity is available after giving effect to uses by co-borrowers Dominion Energy, Virginia Power and Dominion Energy Gas. Sub-limits for Questar Gas are set within the facility limit but can be changed at the option of the borrowers multiple times per year. At June 30, 2017, the sub-limit for Questar Gas was an aggregate $250 million. If Questar Gas has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term intercompany borrowings from Dominion Energy. The maturity date for these facilities is April 2020. These credit facilities can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit .

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 10. Commitments and Contingencies As a result of issues generated in the ordinary course of business, Questar Gas is involved in legal proceedings before various courts and is periodically subject to governmental examinations (including by regulatory authorities), 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 Questar Gas to estimate a range of possible loss. For such matters for which Questar Gas cannot estimate a range of possible loss, 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 Questar Gas is able to estimate a range of possible loss. For legal proceedings and governmental examinations for which Questar Gas 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. Any accrued liability is recorded on a gross basis with a receivable also recorded for any probable insurance recoveries. 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 estimated range of possible loss may not represent Questar Gas' 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. For current proceedings not specifically reported below, management does not anticipate that the liabilities, if any, arising from such proceedings would have a material effect on the financial position, liquidity or results of operations of Questar Gas. The CERCLA, as amended, provides for immediate response and removal actions coordinated by the EPA in the event of threatened releases of hazardous substances into the environment and authorizes the U.S. government either to clean up sites at which hazardous substances have created actual or potential environmental hazards or to order persons responsible for the situation to do so. Under the CERCLA, as amended, generators and transporters of hazardous substances, as well as past and present owners and operators of contaminated sites, can be jointly, severally and strictly liable for the cost of cleanup. These potentially responsible parties can be ordered to perform a cleanup, be sued for costs associated with an EPA-directed cleanup, voluntarily settle with the U.S. government concerning their liability for cleanup costs, or voluntarily begin a site investigation and site remediation under state oversight. Questar Gas has determined that it is associated with two former manufactured gas plant sites that contain coal tar and other potentially harmful materials. None of the former sites with which Questar Gas is associated is under investigation by any state or federal environmental agency. Due to the uncertainty surrounding the sites, Questar Gas is unable to make an estimate of the potential financial statement impacts.

Credit Risk

Credit Risk	6 Months Ended
	Jun. 30, 2017
Risks And Uncertainties [Abstract]
Credit Risk	Note 11. Credit Risk Questar Gas' accounting policies for credit risk are discussed in Note 17 to the Financial Statements in Questar Gas' Annual Report on Form 10-K for the year ended December 31, 2016. Questar Gas maintains a provision for credit losses based on factors surrounding the credit risk of its customers, historical trends and other information. Management believes, based on credit policies and the June 30, 2017 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	6 Months Ended
	Jun. 30, 2017
Related Party Transactions [Abstract]
Related-Party Transactions	Note 12. Related-Party Transactions Questar Gas engages in related party-transactions primarily with affiliates Wexpro, for cost-of-service natural gas supply, and Dominion Energy Questar Pipeline, for transportation and storage services. Questar Gas' receivables and payables balances with affiliates are settled based on contractual terms or on a monthly basis, depending on the nature of the underlying transactions. A discussion of significant related party transactions follows. Dominion Energy Questar and other affiliates provide accounting, legal, finance and certain administrative and technical services to Questar Gas. These costs are included in other operations and maintenance in the Statements of Income. The administrative charges are generally allocated based on each affiliated company's proportional share of revenues less product costs; property, plant and equipment; and labor costs. Management believes that the allocation method is reasonable. Questar Gas provides certain services to related parties, including technical services. The billed amounts of these services are allocated based on the specific nature of the charges. Management believes that the allocation methods are reasonable. The amounts of these services follow: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 (millions) Affiliated operator service fee (1) $ 79.7 $ 78.9 $ 155.6 $ 158.7 Transportation and storage services from affiliates (1) 17.3 17.3 36.9 36.5 Services provided by related parties 11.1 12.6 21.9 26.1 Services provided to related parties 1.4 0.5 2.9 1.0 (1) The costs of these services were included in cost of sales in Questar Gas' Statements of Income. Questar Gas participates in certain Dominion Energy Questar benefit plans as described in Note 15 to the Financial Statements in Questar Gas' Annual Report on Form 10-K for the year ended December 31, 2016. At June 30, 2017 and December 31, 2016, amounts due from Dominion Energy Questar associated with the Questar Corporation Retirement Plan and included in receivables from affiliates in the Balance Sheets were $98.6 million and $87.8 million, respectively. Questar Gas recorded a pension expense (credit) related to this plan of $(4.4) million and $2.8 million for the six months ended June 30, 2017 and 2016, respectively. At June 30, 2017 and December 31, 2016, Questar Gas' amounts due to Dominion Energy Questar associated with the Questar Corporation Umbrella Health Plan and included in payables to affiliates in the Balance Sheets were $12.8 million and $13.0 million, respectively. The Dominion Energy Questar Combination resulted in merger and restructuring costs of $6.4 million and $6.7 million for the three and six months ended June 30, 2017, respectively, charged from Dominion Energy Questar. There were no merger and restructuring costs for the three and six months ended June 30, 2016. These costs primarily consist of employee related costs allocated to Questar Gas and are included in other operations and maintenance in Questar Gas' Statements of Income. Questar Gas’ borrowings under the IRCA with Dominion Energy totaled $10.0 million as of June 30, 2017 and $48.0 million at December 31, 2016. The weighted-average interest rate for these borrowing was 1.36% as of June 30, 2017. Interest charges related to Questar Gas' total borrowings from Dominion Energy and Dominion Energy Questar were less than $0.1 million for the three and six months ended June 30, 2017 and $0.2 million and $0.5 million for the three and six months ended June 30, 2016, respectively. In March 2017, Questar Gas entered into agreements, at rates and on terms and conditions that are subject to regulation by FERC, with Dominion Energy Questar Pipeline to extend transportation services through 2027. Under these agreements, Questar Gas will pay Dominion Energy Questar Pipeline approximately $55 million annually. Also in March 2017, Questar Gas extended a storage contract, at rates and on terms and conditions that are subject to regulation by FERC, with Dominion Energy Questar Pipeline through 2022. Under this extension, Questar Gas will pay Dominion Energy Questar Pipeline approximately $2 million annually.

Operating Segment

Operating Segment	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Operating Segment	Note 13. Operating Segment The Corporate and Other Segment primarily includes specific items attributable to Questar Gas' operating segment, Gas Infrastructure (previously named Questar Gas), that are not included in profit measures evaluated by executive management in assessing the segment's performance or in allocating resources. The net expense for specific items in 2017 primarily related to an $11.4 million ($7.1 million after-tax) charge for merger and restructuring costs associated with the Dominion Energy Questar Combination. These costs include employee related costs allocated to Questar Gas and are included in other operations and maintenance in Questar Gas' Statements of Income. The following table presents segment information pertaining to Questar Gas' operations: Gas Infrastructure Corporate and Other Consolidated Total (millions) Three Months Ended June 30, 2017 Operating revenue $ 139.7 $ — $ 139.7 Net income (loss) 0.7 (6.9 ) (6.2 ) Three Months Ended June 30, 2016 Operating revenue $ 128.2 $ — $ 128.2 Net loss (1.6 ) — (1.6 ) Six Months Ended June 30, 2017 Operating revenue $ 536.6 $ — $ 536.6 Net income (loss) 53.1 (7.1 ) 46.0 Six Months Ended June 30, 2016 Operating revenue $ 536.1 $ — $ 536.1 Net income 46.0 — 46.0

Significant Accounting Polici19

Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation	As permitted by the rules and regulations of the SEC, Questar Gas' accompanying unaudited Financial Statements contain certain condensed financial information and exclude certain footnote disclosures normally included in annual audited financial statements prepared in accordance with GAAP.
Use of Estimates	Questar Gas makes certain estimates and assumptions in preparing its 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, expenses and cash flows for the periods presented. Actual results may differ from those estimates.
Fair Value Measurements	Questar Gas reports certain contracts and instruments at fair value. Questar Gas enters into certain physical forwards and options, which are considered Level 3 as they have one or more inputs that are not observable and are significant to the valuation. The discounted cash flow method is used to value Level 3 physical forward contracts. An option model is used to value Level 3 physical options. The discounted cash flow model for forwards calculates mark-to-market valuations based on forward market prices, original transaction prices, volumes, risk-free rate of return, and credit spreads. The option model calculates mark-to-market valuations using variations of the Black-Scholes option model. The inputs into the models are the forward market prices, implied price volatilities, risk-free rate of return, the option expiration dates, the option strike prices, the original sales prices, and volumes.
Reclassifications	Certain amounts in the 2016 Financial Statements and Notes have been reclassified to conform to the 2017 presentation for comparative purposes. The reclassifications did not affect Questar Gas' net income, total assets, liabilities, equity or cash flows
Derivatives	Derivative assets and liabilities are presented gross on Questar Gas' Balance Sheets. Questar Gas' derivative contracts include over-the-counter transactions, which are bilateral contracts that are transacted directly with a counterparty. At June 30, 2017, substantially all of Questar Gas' derivative assets and liabilities were not subject to a master netting or similar arrangement.
Commitments and Contingencies	As a result of issues generated in the ordinary course of business, Questar Gas is involved in legal proceedings before various courts and is periodically subject to governmental examinations (including by regulatory authorities), 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 Questar Gas to estimate a range of possible loss. For such matters for which Questar Gas cannot estimate a range of possible loss, 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 Questar Gas is able to estimate a range of possible loss. For legal proceedings and governmental examinations for which Questar Gas 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. Any accrued liability is recorded on a gross basis with a receivable also recorded for any probable insurance recoveries. 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 estimated range of possible loss may not represent Questar Gas' 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.
Credit Risk	Questar Gas maintains a provision for credit losses based on factors surrounding the credit risk of its customers, historical trends and other information. Management believes, based on credit policies and the June 30, 2017 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.

Operating Revenue (Tables)

Operating Revenue (Tables)	6 Months Ended
	Jun. 30, 2017
Regulated And Unregulated Operating Revenue [Abstract]
Operating Revenue	Questar Gas' operating revenue consists of the following: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 (millions) Residential and commercial gas sales $ 122.0 $ 112.9 $ 500.5 $ 504.6 Industrial gas sales 3.1 4.5 6.3 9.5 Gas transportation 6.3 5.7 13.2 11.7 Other (1) 8.3 5.1 16.6 10.3 Total operating revenue $ 139.7 $ 128.2 $ 536.6 $ 536.1 (1) See Note 11 for amounts attributable to related parties.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Quantitative Information About Level 3 Fair Value Measurements	The following table presents Questar Gas' quantitative information about Level 3 fair value measurements at June 30, 2017. The range and weighted average are presented in dollars for market price inputs and percentages for price volatility Fair Value (millions) Valuation Techniques Unobservable Input Range Weighted Average (1) Assets Physical options: Natural gas $ 0.3 Option model Market price (per Dth) (2 ) 3.2 - 3.4 3.3 Price volatility (3 ) 25.1% - 31.7% 27.7 % Total assets $ 0.3 Liabilities Physical forwards: Natural gas (4) $ 0.5 Discounted cash flow Market price (per Dth) (2 ) 2.3 - 3.4 2.9 Total liabilities $ 0.5 (1) Averages weighted by volume. (2 ) Represents market prices beyond defined terms for Level 1 and 2. (3 ) Represents volatilities unrepresented in published markets. (4 ) Includes basis.
Sensitivity of Fair Value Measurements to Changes in Unobservable Inputs	Sensitivity of the fair value measurements to changes in the significant unobservable inputs is as follows: Significant Unobservable Inputs Position Change to Input Impact on Fair Value Measurement Market price Buy Increase (decrease) Gain (loss) Market price Sell Increase (decrease) Loss (gain) Price volatility Buy Increase (decrease) Gain (loss) Price volatility Sell Increase (decrease) Loss (gain)
Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following table presents Questar Gas’ assets and liabilities that are measured at fair value on a recurring basis for each hierarchy level, including both current and noncurrent portions. Level 1 Level 2 Level 3 Total (millions) At June 30, 2017 Assets: Derivatives: Commodity $ — $ — $ 0.3 $ 0.3 Total assets $ — $ — $ 0.3 $ 0.3 Liabilities: Derivatives: Commodity $ — $ 0.1 $ 0.5 $ 0.6 Total liabilities $ — $ 0.1 $ 0.5 $ 0.6 At December 31, 2016 Assets: Derivatives: Commodity $ — $ 0.1 $ — $ 0.1 Total assets $ — $ 0.1 $ — $ 0.1 Liabilities: Derivatives: Commodity $ — $ 0.1 $ — $ 0.1 Total liabilities $ — $ 0.1 $ — $ 0.1
Fair Value Assets and Liabilities Measured on Recurring Basis Unobservable Input Reconciliation	The following table presents the net change in Questar Gas' assets and liabilities measured at fair value on a recurring basis and included in the Level 3 fair value category. Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 (millions) Beginning balance $ (1.3 ) $ — $ — $ — Total realized and unrealized gains (losses): Included in earnings (1) — — (0.1 ) — Included in regulatory assets/liabilities 1.0 — (0.3 ) — Settlements — — 0.1 — Purchases 0.1 — 0.1 — Ending balance $ (0.2 ) $ — $ (0.2 ) $ — (1) The gains and losses included in earnings were classified in cost of sales.
Schedule Carrying Amounts and Estimated Fair Value of Financial Instruments not Recorded at Fair Value	For Questar Gas' financial instruments that are not recorded at fair value, the carrying amounts and estimated fair values are as follows: June 30, 2017 December 31, 2016 Carrying Amount Estimated Fair Value (1) Carrying Amount Estimated Fair Value (1) (millions) Long-term debt, including securities due within one year (2) $ 631.0 $ 687.1 $ 630.8 $ 672.6 (1) Fair value is estimated using market prices, where available, and interest rates currently available for issuance of debt with similar terms and remaining maturities. The fair value measurements are classified as Level 2. (2) Carrying amount includes amounts which represent the unamortized debt issuance costs, discount or premium.

Derivatives and Hedge Account22

Derivatives and Hedge Accounting Activities (Tables)	6 Months Ended
	Jun. 30, 2017
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Schedule of Notional Amounts of Outstanding Derivative Positions	The following table presents the volume of Questar Gas' derivative activity at June 30, 2017. These volumes are based on open derivative positions and represent the combined absolute value of its long and short positions, except in the case of offsetting transactions, for which they represent the absolute value of the net volume of its long and short positions. Current Noncurrent Natural Gas (bcf): Basis 12.1 25.9
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The following table presents the fair values of Questar Gas' derivatives and where they are presented in its Balance Sheets. Fair Value - Derivatives not under Hedge Accounting Total Fair Value (millions) At June 30, 2017 ASSETS Current Assets Commodity $ 0.3 $ 0.3 Total current derivative assets (1) 0.3 0.3 Total derivative assets $ 0.3 $ 0.3 LIABILITIES Current Liabilities Commodity $ 0.2 $ 0.2 Total current derivative liabilities (2) 0.2 0.2 Noncurrent Liabilities Commodity 0.4 0.4 Total noncurrent derivative liabilities (3) 0.4 0.4 Total derivative liabilities $ 0.6 $ 0.6 At December 31, 2016 ASSETS Current Assets Commodity $ 0.1 $ 0.1 Total current derivative assets (1) 0.1 0.1 Total derivative assets $ 0.1 $ 0.1 LIABILITIES Current Liabilities Commodity $ 0.1 $ 0.1 Total current derivative liabilities (2) 0.1 0.1 Total derivative liabilities $ 0.1 $ 0.1 (1) Current derivative assets are presented in other current assets in Questar Gas' Balance Sheets. (2) Current derivative liabilities are presented in other current liabilities in Questar Gas’ Balance Sheets. (3) Noncurrent derivative liabilities are presented in other noncurrent liabilities in Questar Gas' Balance Sheets.
Derivative Instruments, Gain (Loss)	The following table presents the gains and losses on Questar Gas' derivatives, as well as where the associated activity is presented in its Statements of Income. Amount (1) Three Months Ended June 30, Six Months Ended June 30, Derivatives not designated as hedging instruments 2017 2016 2017 2016 (millions) Derivative Type and Location of Gains (Losses) Commodity (2) $ — $ — $ (0.5 ) $ — Total $ — $ — $ (0.5 ) $ — (1) Includes derivative activity amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/liabilities have no associated effect in Questar Gas' Statements of Income. (2) Amounts recorded in Questar Gas' Statements of Income are classified in cost of sales .

Regulatory Assets and Liabili23

Regulatory Assets and Liabilities (Tables)	6 Months Ended
	Jun. 30, 2017
Regulated Operations [Abstract]
Schedule of Regulatory Assets	Regulatory assets and liabilities include the following: June 30, December 31, 2017 2016 (millions) Regulatory assets: Purchased-gas adjustment (1) $ 10.8 $ 3.4 Contract withholding (2) — 2.6 Pipeline integrity costs (3) 1.9 1.9 Other 0.7 1.7 Regulatory assets-current 13.4 9.6 Cost of reacquired debt (4) 2.9 3.2 Pipeline integrity costs (3) 1.1 2.3 Other 0.4 — Regulatory assets-noncurrent (5) 4.4 5.5 Total regulatory assets $ 17.8 $ 15.1 Regulatory liabilities: Cost of plant removal and AROs (6) $ 5.0 $ 3.5 CET (7) 2.3 2.9 Curtailment penalty (8) 1.1 — Other 0.7 0.1 Regulatory liabilities-current 9.1 6.5 Cost of plant removal and AROs (6) 190.8 189.1 Regulatory liabilities-noncurrent 190.8 189.1 Total regulatory liabilities $ 199.9 $ 195.6 (1) Purchased-gas costs that are different from those provided for in present rates are accumulated and recovered or credited through future rate changes. ( 2 ) Represents a disputed amount withheld from a supplier of storage services. The dispute was settled in March 2017 and the amount reversed, which resulted in no material impact to Questar Gas' results of operations, financial position or cash flows. ( 3 ) The costs of complying with pipeline-integrity regulations are recovered in rates subject to a Utah Commission order. Questar Gas is allowed to recover $7.0 million per year. Costs incurred in excess of this amount will be recovered in future rate changes. ( 4 ) Gains and losses on the reacquisition of debt by rate-regulated companies are deferred and amortized as interest expense over the would-be remaining life of the reacquired debt. The reacquired debt costs had a weighted-average life of approximately 5.6 years as of June 30, 2017. ( 5 ) Noncurrent regulatory assets are presented in other noncurrent assets in the Balance Sheets. ( 6 ) Cost of plant removal and AROs represent amounts recovered from customers for costs of future activities to remove assets that are expected to be incurred at the time of retirement. ( 7 ) Represents the difference between actual and allowed revenues. Any deficiency in amounts collected is recovered through periodic rate adjustments. ( 8 ) Interruptible customers who fail to interrupt service when called upon by Questar Gas incur a curtailment penalty. Penalties recovered by Questar Gas are credited to ratepayers as a reduction to the infrastructure-replacement program.
Schedule of Regulatory Liabilities	Regulatory assets and liabilities include the following: June 30, December 31, 2017 2016 (millions) Regulatory assets: Purchased-gas adjustment (1) $ 10.8 $ 3.4 Contract withholding (2) — 2.6 Pipeline integrity costs (3) 1.9 1.9 Other 0.7 1.7 Regulatory assets-current 13.4 9.6 Cost of reacquired debt (4) 2.9 3.2 Pipeline integrity costs (3) 1.1 2.3 Other 0.4 — Regulatory assets-noncurrent (5) 4.4 5.5 Total regulatory assets $ 17.8 $ 15.1 Regulatory liabilities: Cost of plant removal and AROs (6) $ 5.0 $ 3.5 CET (7) 2.3 2.9 Curtailment penalty (8) 1.1 — Other 0.7 0.1 Regulatory liabilities-current 9.1 6.5 Cost of plant removal and AROs (6) 190.8 189.1 Regulatory liabilities-noncurrent 190.8 189.1 Total regulatory liabilities $ 199.9 $ 195.6 (1) Purchased-gas costs that are different from those provided for in present rates are accumulated and recovered or credited through future rate changes. ( 2 ) Represents a disputed amount withheld from a supplier of storage services. The dispute was settled in March 2017 and the amount reversed, which resulted in no material impact to Questar Gas' results of operations, financial position or cash flows. ( 3 ) The costs of complying with pipeline-integrity regulations are recovered in rates subject to a Utah Commission order. Questar Gas is allowed to recover $7.0 million per year. Costs incurred in excess of this amount will be recovered in future rate changes. ( 4 ) Gains and losses on the reacquisition of debt by rate-regulated companies are deferred and amortized as interest expense over the would-be remaining life of the reacquired debt. The reacquired debt costs had a weighted-average life of approximately 5.6 years as of June 30, 2017. ( 5 ) Noncurrent regulatory assets are presented in other noncurrent assets in the Balance Sheets. ( 6 ) Cost of plant removal and AROs represent amounts recovered from customers for costs of future activities to remove assets that are expected to be incurred at the time of retirement. ( 7 ) Represents the difference between actual and allowed revenues. Any deficiency in amounts collected is recovered through periodic rate adjustments. ( 8 ) Interruptible customers who fail to interrupt service when called upon by Questar Gas incur a curtailment penalty. Penalties recovered by Questar Gas are credited to ratepayers as a reduction to the infrastructure-replacement program.

Significant Financing Transac24

Significant Financing Transactions (Tables)	6 Months Ended
	Jun. 30, 2017
Short Term Debt Other Disclosures [Abstract]
Schedule of Short-term Debt	At June 30, 2017, Questar Gas' commercial paper and letters of credit outstanding under its joint credit facilities with Dominion Energy, Virginia Power and Dominion Energy Gas, were as follows: Facility Limit (1) Outstanding Commercial Paper Outstanding Letters of Credit (millions) Joint revolving credit facility (1) $ 500.0 $ 135.0 $ — Joint revolving credit facility (1) 500.0 — — Total $ 1,000.0 $ 135.0 $ — (1) A maximum of a combined $1.0 billion of the facilities is available to Questar Gas, assuming adequate capacity is available after giving effect to uses by co-borrowers Dominion Energy, Virginia Power and Dominion Energy Gas. Sub-limits for Questar Gas are set within the facility limit but can be changed at the option of the borrowers multiple times per year. At June 30, 2017, the sub-limit for Questar Gas was an aggregate $250 million. If Questar Gas has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term intercompany borrowings from Dominion Energy. The maturity date for these facilities is April 2020. These credit facilities can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit .

Related-Party Transactions (Tab

Related-Party Transactions (Tables)	6 Months Ended
	Jun. 30, 2017
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	The amounts of these services follow: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 (millions) Affiliated operator service fee (1) $ 79.7 $ 78.9 $ 155.6 $ 158.7 Transportation and storage services from affiliates (1) 17.3 17.3 36.9 36.5 Services provided by related parties 11.1 12.6 21.9 26.1 Services provided to related parties 1.4 0.5 2.9 1.0 (1) The costs of these services were included in cost of sales in Questar Gas' Statements of Income.

Operating Segment (Tables)

Operating Segment (Tables)	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	The following table presents segment information pertaining to Questar Gas' operations: Gas Infrastructure Corporate and Other Consolidated Total (millions) Three Months Ended June 30, 2017 Operating revenue $ 139.7 $ — $ 139.7 Net income (loss) 0.7 (6.9 ) (6.2 ) Three Months Ended June 30, 2016 Operating revenue $ 128.2 $ — $ 128.2 Net loss (1.6 ) — (1.6 ) Six Months Ended June 30, 2017 Operating revenue $ 536.6 $ — $ 536.6 Net income (loss) 53.1 (7.1 ) 46.0 Six Months Ended June 30, 2016 Operating revenue $ 536.1 $ — $ 536.1 Net income 46.0 — 46.0

Operating Revenue (Details)

Operating Revenue (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Public Utilities, General Disclosures [Line Items]
Gas transportation		$ 6.3	$ 5.7	$ 13.2	$ 11.7
Other	[1]	8.3	5.1	16.6	10.3
Total operating revenue	[2]	139.7	128.2	536.6	536.1
Residential and commercial
Public Utilities, General Disclosures [Line Items]
Residential, commercial, and industrial sales		122	112.9	500.5	504.6
Industrial
Public Utilities, General Disclosures [Line Items]
Residential, commercial, and industrial sales		$ 3.1	$ 4.5	$ 6.3	$ 9.5
[1]	See Note 11 for amounts attributable to related parties.
[2]	See Note 12 for amounts attributable to related parties.

Fair Value Measurements - Quant

Fair Value Measurements - Quantitative Information About Level 3 Fair Value Measurements (Details) $ in Millions		6 Months Ended
		Jun. 30, 2017USD ($)$ / MMBTU	Dec. 31, 2016USD ($)
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Derivative assets		$ 0.3	$ 0.1
Derivative liabilities		0.6	0.1
Fair Value, Measurements, Recurring | Commodity
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Derivative assets		0.3	0.1
Derivative liabilities		0.6	0.1
Level 3 | Fair Value, Measurements, Recurring
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Derivative assets		0.3
Derivative liabilities		0.5
Level 3 | Fair Value, Measurements, Recurring | Commodity
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Derivative assets		0.3	0
Derivative liabilities		0.5	$ 0
Level 3 | Fair Value, Measurements, Recurring | Natural Gas | Commodity | Option model
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Derivative assets		$ 0.3
Level 3 | Fair Value, Measurements, Recurring | Natural Gas | Commodity | Option model | Minimum | Derivative Financial Instruments, Assets
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Fair value inputs, price | $ / MMBTU	[1]	3.2
Price volatility (percentage)	[2]	25.10%
Level 3 | Fair Value, Measurements, Recurring | Natural Gas | Commodity | Option model | Maximum | Derivative Financial Instruments, Assets
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Fair value inputs, price | $ / MMBTU	[1]	3.4
Price volatility (percentage)	[2]	31.70%
Level 3 | Fair Value, Measurements, Recurring | Natural Gas | Commodity | Option model | Weighted Average | Derivative Financial Instruments, Assets
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Fair value inputs, price | $ / MMBTU	[3]	3.3
Price volatility (percentage)	[3]	27.70%
Level 3 | Fair Value, Measurements, Recurring | Natural Gas | Commodity | Discounted cash flow
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Derivative liabilities	[4]	$ 0.5
Level 3 | Fair Value, Measurements, Recurring | Natural Gas | Commodity | Discounted cash flow | Minimum | Derivative Financial Instruments, Liabilities
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Fair value inputs, price | $ / MMBTU	[1]	2.3
Level 3 | Fair Value, Measurements, Recurring | Natural Gas | Commodity | Discounted cash flow | Maximum | Derivative Financial Instruments, Liabilities
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Fair value inputs, price | $ / MMBTU	[1]	3.4
Level 3 | Fair Value, Measurements, Recurring | Natural Gas | Commodity | Discounted cash flow | Weighted Average | Derivative Financial Instruments, Liabilities
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Fair value inputs, price | $ / MMBTU	[3]	2.9
[1]	Represents market prices beyond defined terms for Level 1 and 2.
[2]	Represents volatilities unrepresented in published markets.
[3]	Averages weighted by volume.
[4]	Includes basis.

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Assets:
Derivatives assets	$ 0.3	$ 0.1
Liabilities:
Derivative liabilities	0.6	0.1
Fair Value, Measurements, Recurring
Assets:
Total assets	0.3	0.1
Liabilities:
Total liabilities	0.6	0.1
Fair Value, Measurements, Recurring | Commodity
Assets:
Derivatives assets	0.3	0.1
Liabilities:
Derivative liabilities	0.6	0.1
Fair Value, Measurements, Recurring | Level 1
Assets:
Total assets	0	0
Liabilities:
Total liabilities	0	0
Fair Value, Measurements, Recurring | Level 1 | Commodity
Assets:
Derivatives assets	0	0
Liabilities:
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Level 2
Assets:
Total assets	0	0.1
Liabilities:
Total liabilities	0.1	0.1
Fair Value, Measurements, Recurring | Level 2 | Commodity
Assets:
Derivatives assets	0	0.1
Liabilities:
Derivative liabilities	0.1	0.1
Fair Value, Measurements, Recurring | Level 3
Assets:
Derivatives assets	0.3
Total assets	0.3	0
Liabilities:
Derivative liabilities	0.5
Total liabilities	0.5	0
Fair Value, Measurements, Recurring | Level 3 | Commodity
Assets:
Derivatives assets	0.3	0
Liabilities:
Derivative liabilities	$ 0.5	$ 0

Fair Value Measurements - Net C

Fair Value Measurements - Net Change in Assets and Liabilities Measured at Fair Value on a Recurring Basis and Included in the Level 3 Fair Value Category (Details) - Commodity - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance		$ (1.3)	$ 0	$ 0	$ 0
Included in earnings	[1]	0	0	(0.1)	0
Included in regulatory assets/liabilities		1	0	(0.3)	0
Settlements		0	0	0.1	0
Purchases		0.1	0	0.1	0
Ending balance		$ (0.2)	$ 0	$ (0.2)	$ 0
[1]	The gains and losses included in earnings were classified in cost of sales.

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Unrealized gains or losses included in earnings in the Level 3 fair value category	$ 0	$ 0

Fair Value Measurements - Sch32

Fair Value Measurements - Schedule of Carrying Amounts and Estimated Fair Values of Financial Instruments not Recorded at Fair Value (Details) - USD ($) $ in Millions		Jun. 30, 2017	Dec. 31, 2016
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including securities due within one year	[1]	$ 631	$ 630.8
Estimated Fair Value | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including securities due within one year	[1],[2]	$ 687.1	$ 672.6
[1]	Carrying amount includes amounts which represent the unamortized debt issuance costs, discount or premium.
[2]	Fair value is estimated using market prices, where available, and interest rates currently available for issuance of debt with similar terms and remaining maturities. The fair value measurements are classified as Level 2.

Derivatives and Hedge Account33

Derivatives and Hedge Accounting Activities - Schedule of Volume of Derivative Activity (Details)	6 Months Ended
	Jun. 30, 2017MMcf
Fixed Price - Natural Gas - Current Derivative Contract
Derivative [Line Items]
Volume of derivative activity (bcf)	12,100
Fixed Price - Natural Gas - Non-current Derivative Contract
Derivative [Line Items]
Volume of derivative activity (bcf)	25,900

Derivatives and Hedge Account34

Derivatives and Hedge Accounting Activities - Schedule of Fair Values of Derivatives and Balance Sheet Location (Details) - USD ($) $ in Millions		Jun. 30, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivatives assets		$ 0.3	$ 0.1
Derivative liabilities		0.6	0.1
Current Assets
Derivatives, Fair Value [Line Items]
Derivatives assets	[1]	0.3	0.1
Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	[2]	0.2	0.1
Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	[3]	0.4
Commodity | Current Assets
Derivatives, Fair Value [Line Items]
Derivatives assets		0.3	0.1
Commodity | Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities		0.2	0.1
Commodity | Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities		0.4
Fair Value - Derivatives not under Hedge Accounting
Derivatives, Fair Value [Line Items]
Derivatives assets		0.3	0.1
Derivative liabilities		0.6	0.1
Fair Value - Derivatives not under Hedge Accounting | Current Assets
Derivatives, Fair Value [Line Items]
Derivatives assets	[1]	0.3	0.1
Fair Value - Derivatives not under Hedge Accounting | Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	[2]	0.2	0.1
Fair Value - Derivatives not under Hedge Accounting | Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	[3]	0.4
Fair Value - Derivatives not under Hedge Accounting | Commodity | Current Assets
Derivatives, Fair Value [Line Items]
Derivatives assets		0.3	0.1
Fair Value - Derivatives not under Hedge Accounting | Commodity | Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities		0.2	$ 0.1
Fair Value - Derivatives not under Hedge Accounting | Commodity | Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities		$ 0.4
[1]	Current derivative assets are presented in other current assets in Questar Gas' Balance Sheets.
[2]	Current derivative liabilities are presented in other current liabilities in Questar Gas’ Balance Sheets.
[3]	Noncurrent derivative liabilities are presented in other noncurrent liabilities in Questar Gas' Balance Sheets.

Derivatives and Hedge Account35

Derivatives and Hedge Accounting Activities - Schedule of Gains and Losses on Derivatives (Details) - Derivatives not designated as hedging instruments $ in Millions	6 Months Ended
	Jun. 30, 2017USD ($)	[1]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	$ (0.5)
Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	$ (0.5)	[2]
[1]	Includes derivative activity amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/liabilities have no associated effect in Questar Gas' Statements of Income.
[2]	Amounts recorded in Questar Gas' Statements of Income are classified in cost of sales.

Regulatory Assets and Liabili36

Regulatory Assets and Liabilities - Regulatory Assets (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2017	Dec. 31, 2016
Regulatory Assets [Line Items]
Regulatory assets-current		$ 13.4	$ 9.6	[1]
Regulatory assets-noncurrent	[2]	4.4	5.5
Total regulatory assets		17.8	15.1
Purchased-gas adjustment
Regulatory Assets [Line Items]
Regulatory assets-current	[3]	10.8	3.4
Contract withholding
Regulatory Assets [Line Items]
Regulatory assets-current	[4]	0	2.6
Pipeline integrity costs
Regulatory Assets [Line Items]
Regulatory assets-current	[5]	1.9	1.9
Regulatory assets-noncurrent	[5]	1.1	2.3
Pipeline integrity costs | Maximum
Regulatory Assets [Line Items]
Allowed recovery amount per year		7
Other
Regulatory Assets [Line Items]
Regulatory assets-current		0.7	1.7
Regulatory assets-noncurrent		0.4
Cost of reacquired debt
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[6]	$ 2.9	$ 3.2
Cost of reacquired debt | Weighted Average
Regulatory Assets [Line Items]
Recovery period		5 years 7 months 6 days
[1]	Questar Gas' Balance Sheet at December 31, 2016 has been derived from the audited Balance Sheet at that date.
[2]	Noncurrent regulatory assets are presented in other noncurrent assets in the Balance Sheets.
[3]	Purchased-gas costs that are different from those provided for in present rates are accumulated and recovered or credited through future rate changes.
[4]	Represents a disputed amount withheld from a supplier of storage services. The dispute was settled in March 2017 and the amount reversed, which resulted in no material impact to Questar Gas' results of operations, financial position or cash flows.
[5]	The costs of complying with pipeline-integrity regulations are recovered in rates subject to a Utah Commission order. Questar Gas is allowed to recover $7.0 million per year. Costs incurred in excess of this amount will be recovered in future rate changes.
[6]	Gains and losses on the reacquisition of debt by rate-regulated companies are deferred and amortized as interest expense over the would-be remaining life of the reacquired debt. The reacquired debt costs had a weighted-average life of approximately 5.6 years as of June 30, 2017.

Regulatory Assets and Liabili37

Regulatory Assets and Liabilities - Regulatory Liabilities (Details) - USD ($) $ in Millions		Jun. 30, 2017	Dec. 31, 2016
Regulatory Liabilities [Line Items]
Regulatory liabilities		$ 9.1	$ 6.5	[1]
Regulatory liabilities, noncurrent		190.8	189.1	[1]
Total regulatory liabilities		199.9	195.6
CET
Regulatory Liabilities [Line Items]
Regulatory liabilities	[2]	2.3	2.9
Curtailment penalty
Regulatory Liabilities [Line Items]
Regulatory liabilities	[3]	1.1
Cost of plant removal and ARO's
Regulatory Liabilities [Line Items]
Regulatory liabilities	[4]	5	3.5
Regulatory liabilities, noncurrent	[4]	190.8	189.1
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities		$ 0.7	$ 0.1
[1]	Questar Gas' Balance Sheet at December 31, 2016 has been derived from the audited Balance Sheet at that date.
[2]	Represents the difference between actual and allowed revenues. Any deficiency in amounts collected is recovered through periodic rate adjustments.
[3]	Interruptible customers who fail to interrupt service when called upon by Questar Gas incur a curtailment penalty. Penalties recovered by Questar Gas are credited to ratepayers as a reduction to the infrastructure-replacement program.
[4]	Cost of plant removal and AROs represent amounts recovered from customers for costs of future activities to remove assets that are expected to be incurred at the time of retirement.

Regulatory Matters (Details)

Regulatory Matters (Details)	Jun. 30, 2017regulatory_commission
Regulated Operations [Abstract]
Number of regulatory commissions	2

Variable Interest Entity (Detai

Variable Interest Entity (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	[1]
Variable Interest Entity [Line Items]
Amounts due to VIE	$ 1,718.3	$ 1,718.3	$ 1,848.9
DEQPS
Variable Interest Entity [Line Items]
Purchased shared services from VIE	0.3	0.7
Amounts due to VIE	$ 0.1	$ 0.1
[1]	Questar Gas' Balance Sheet at December 31, 2016 has been derived from the audited Balance Sheet at that date.

Significant Financing Transac40

Significant Financing Transactions (Details)	6 Months Ended
	Jun. 30, 2017USD ($)Facility
Line of Credit Facility [Line Items]
Facility Limit	$ 1,000,000,000	[1]
Outstanding Commercial Paper	135,000,000	[1]
Outstanding Letters of Credit	0
Credit Facility $5 Billion
Line of Credit Facility [Line Items]
Facility Limit	500,000,000	[1]
Outstanding Commercial Paper	135,000,000	[1]
Outstanding Letters of Credit	0	[1]
Credit Facility $500 Million
Line of Credit Facility [Line Items]
Facility Limit	500,000,000	[1]
Outstanding Commercial Paper	0	[1]
Outstanding Letters of Credit	$ 0	[1]
Joint Revolving Credit Facility $5 Billion and Joint Revolving Credit Facility $500 Million
Line of Credit Facility [Line Items]
Number of joint revolving credit facility | Facility	2
Facility Limit	$ 1,000,000,000
Joint Revolving Credit Facility $5 Billion and Joint Revolving Credit Facility $500 Million | Line of Credit
Line of Credit Facility [Line Items]
Amount of sub-limit	250,000,000
Joint Revolving Credit Facility $5 Billion and Joint Revolving Credit Facility $500 Million | Letter of Credit
Line of Credit Facility [Line Items]
Facility Limit	$ 1,000,000,000
[1]	A maximum of a combined $1.0 billion of the facilities is available to Questar Gas, assuming adequate capacity is available after giving effect to uses by co-borrowers Dominion Energy, Virginia Power and Dominion Energy Gas. Sub-limits for Questar Gas are set within the facility limit but can be changed at the option of the borrowers multiple times per year. At June 30, 2017, the sub-limit for Questar Gas was an aggregate $250 million. If Questar Gas has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term intercompany borrowings from Dominion Energy. The maturity date for these facilities is April 2020. These credit facilities can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit.

Commitments and Contingencies (

Commitments and Contingencies (Details)	Jun. 30, 2017site
Unfavorable Regulatory Action | Coal Tar and Other Potentially Harmful Materials | EPA
Other Commitments [Line Items]
Number of former manufactured gas plant sites	2

Related-Party Transactions (Det

Related-Party Transactions (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2017	Dec. 31, 2016	[1]
Related Party Transaction [Line Items]
Receivable from affiliates		$ 98.6		$ 98.6			$ 87.8
Pension expense (credit)				(4.4)	$ 2.8
Payables to affiliates		12.8		12.8			13
Affiliated current borrowings		$ 10		$ 10			$ 48
Dominion Energy | IRCA | Revolving Credit Facility
Related Party Transaction [Line Items]
Weighted-average interest rate percentage		1.36%		1.36%
Related party interest expense			$ 0.2		0.5
Dominion Energy | Maximum | IRCA | Revolving Credit Facility
Related Party Transaction [Line Items]
Related party interest expense		$ 0.1		$ 0.1
Affiliated operator service fee
Related Party Transaction [Line Items]
Related party expenses in cost of sales	[2]	79.7	78.9	155.6	158.7
Transportation and storage services from affiliates
Related Party Transaction [Line Items]
Related party expenses in cost of sales	[2]	17.3	17.3	36.9	36.5
Services provided by/to related parties
Related Party Transaction [Line Items]
Related party expenses		11.1	12.6	21.9	26.1
Related party revenues		1.4	0.5	2.9	1
Merger and restructuring costs | Dominion Energy Questar Corporation | Dominion Energy Questar Corporation
Related Party Transaction [Line Items]
Transaction costs		$ 6.4	$ 0	$ 6.7	$ 0
Transportation services | Dominion Energy Questar Pipeline
Related Party Transaction [Line Items]
Annual commitment						$ 55
Storage contract | Dominion Energy Questar Pipeline
Related Party Transaction [Line Items]
Annual commitment						$ 2
[1]	Questar Gas' Balance Sheet at December 31, 2016 has been derived from the audited Balance Sheet at that date.
[2]	The costs of these services were included in cost of sales in Questar Gas' Statements of Income.

Operating Segment - Narrative (

Operating Segment - Narrative (Details) - Corporate and Other - Merger and restructuring costs associated with Dominion Questar combination - Dominion Energy Questar Corporation $ in Millions	6 Months Ended
	Jun. 30, 2017USD ($)
Segment Reporting Information [Line Items]
Transaction costs	$ 11.4
Merger and restructuring costs, net of tax	$ 7.1

Operating Segment - Schedule of

Operating Segment - Schedule of Segment Information (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Operating revenue	[1]	$ 139.7	$ 128.2	$ 536.6	$ 536.1
Net income (loss)		(6.2)	(1.6)	46	46
Gas Infrastructure
Segment Reporting Information [Line Items]
Operating revenue		139.7	128.2	536.6	536.1
Net income (loss)		0.7	(1.6)	53.1	46
Corporate and Other
Segment Reporting Information [Line Items]
Operating revenue		0	0	0	0
Net income (loss)		$ (6.9)	$ 0	$ (7.1)	$ 0
[1]	See Note 12 for amounts attributable to related parties.