Operating Segment (Tables)

9 Months Ended

Sep. 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 September 30, 2017
Operating revenue	$	90.9		$	—		$	90.9
Net loss		(7.0	)		(1.5	)		(8.5	)
Three Months Ended September 30, 2016
Operating revenue	$	87.9		$	—		$	87.9
Net loss		(10.0	)		(7.7	)		(17.7	)
Nine Months Ended September 30, 2017
Operating revenue	$	627.5		$	—		$	627.5
Net income (loss)		46.1			(8.6	)		37.5
Nine Months Ended September 30, 2016
Operating revenue	$	624.0		$	—		$	624.0
Net income (loss)		36.0			(7.7	)		28.3