Basis of Presentation of Interim Financial Statements (Tables)

3 Months Ended

Mar. 31, 2013

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Cost of sales detail [Table Text Block]

The details of Questar's consolidated cost of sales are as follows:

	3 Months Ended						12 Months Ended
	March 31,						March 31,
	2013			2012			2013			2012
	(in millions)
Questar Gas
Gas purchases	$	103.3		$	61.5		$	146.0		$	164.2
Operator service fee	72.8			65.7			281.1			258.3
Transportation and storage	22.0			20.6			81.0			78.0
Gathering	4.6			6.1			19.0			25.2
Royalties	11.1			10.2			32.9			40.7
Storage (injection) withdrawal, net	28.8			27.4			3.3			(2.3		)
Purchased-gas account adjustment	46.7			43.4			19.4			24.0
Other	1.3			1.3			5.0			5.1
Total Questar Gas cost of natural gas sold	290.6			236.2			587.7			593.2
Elimination of Questar Gas cost of natural gas sold - affiliated parties	(92.1		)	(84.0		)	(355.8		)	(331.9		)
Total Questar Gas cost of natural gas sold - unaffiliated parties	198.5			152.2			231.9			261.3
Questar Pipeline
Total Questar Pipeline cost of sales	1.2			0.5			7.4			3.0
Total cost of sales	$	199.7		$	152.7		$	239.3		$	264.3