Document And Entity Information	3 Months Ended
	Mar. 31, 2012	Apr. 30, 2012
Entity Information [Line Items]
Entity Registrant Name	QUESTAR CORP
Entity Central Index Key	0000751652
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		178,197,754
Questar Gas [Member]
Entity Information [Line Items]
Entity Registrant Name	QUESTAR GAS CO
Entity Central Index Key	0000068589
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		9,189,626
Questar Pipeline [Member]
Entity Information [Line Items]
Entity Registrant Name	QUESTAR PIPELINE CO
Entity Central Index Key	0000764044
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		6,550,843