Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2018

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 March 31, 2018.  The range and weighted average are presented in dollars for market price inputs.

	Fair Value (millions)		Valuation Techniques	Unobservable Input			Range	Weighted Average(1)
Assets
Physical forwards:
Natural gas(2)	$	1.4	Discounted cash flow	Market price (per Dth)	(3	)	1.8 - 3.0		2.5
Total assets	$	1.4

(1) Averages weighted by volume.

(2) Includes basis.

(3) Represents market prices beyond defined terms for Level 1 and 2.

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)

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 March 31, 2018
Assets:
Derivatives:
Commodity	$	—	$	—	$	1.4	$	1.4
Total assets	$	—	$	—	$	1.4	$	1.4
At December 31, 2017
Assets:
Derivatives:
Commodity	$	—	$	—	$	2.4	$	2.4
Total assets	$	—	$	—	$	2.4	$	2.4

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 March 31,
	2018			2017
(millions)
Beginning balance	$	2.4		$	—
Total realized and unrealized gains (losses):
Included in earnings(1)		0.1			(0.1	)
Included in regulatory assets/liabilities		(1.0	)		(1.3	)
Settlements		(0.1	)		0.1
Ending balance	$	1.4		$	(1.3	)

(1) The gains and losses included in earnings were classified in purchased gas.

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:

	March 31, 2018				December 31, 2017
	Carrying Amount		Estimated Fair Value(1)		Carrying Amount		Estimated Fair Value(1)
(millions)
Long-term debt, including securities due within one year(2)	$	646.0	$	690.8	$	715.9	$	783.2

(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.