Operating Segment (Tables)

3 Months Ended

Mar. 31, 2018

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 March 31, 2018
Operating revenue	$	406.7	$	—		$	406.7
Net income (loss)		59.3		(0.2	)		59.1
Three Months Ended March 31, 2017
Operating revenue	$	396.9	$	—		$	396.9
Net income (loss)		52.4		(0.2	)		52.2