The after tax average rate of return from operations under the agreement.

No definition available.

Name:	str_AverageAnnualRateOfReturnAfterTax
Namespace Prefix:	str_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Net investment base of the subsidiary.

No definition available.

The amount of operating income received by subsidiary from operations as outlined by the agreement.

No definition available.

Name:	str_OilIncomeSharingAmountsPerAgreement
Namespace Prefix:	str_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The percentage of after-tax return allowed to subsidiary from operations as outlined by the agreement.

No definition available.

Name:	str_PercentageOfAfterTaxRateOfReturn
Namespace Prefix:	str_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The percentage of operating income retained by the subsidiary from operations as outlined by agreement.

No definition available.

Name:	str_PercentageOfOperatingIncomeRetention
Namespace Prefix:	str_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The percentage of operating income retained by subsidiary from operations as outlined by agreement that are other than Wexpro.

No definition available.

Name:	str_PercentageOfOperatingIncomeRetentionGas
Namespace Prefix:	str_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Wexpro Agreement (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Agreement [Line Items]
Percentage of Wexpro retention (in hundredths)	46.00%
Wexpro's net investment base (in millions)	$ 531.1	$ 474.4	$ 456.6
Average annual rate of return (after tax) (in hundredths)	19.90%	20.00%	20.00%
Gas-development drilling [Member]
Agreement [Line Items]
Percentage of Wexpro after tax rate of return (in hundredths)	20.40%
Natural Gas operations [Member]
Agreement [Line Items]
Percentage of Wexpro after tax rate of return (in hundredths)	12.40%
Developmental Oil Drilling [Member]
Agreement [Line Items]
Percentage of Wexpro after tax rate of return (in hundredths)	17.40%
Percentage of Wexpro retention (in hundredths)	46.00%
Percentage of Questar Gas retention (in hundredths)	54.00%
Oil Income Sharing Amounts Per Agreement	$ 2.5	$ 3.3	$ 1.1
Crude Oil Production [Member]
Agreement [Line Items]
Percentage of Wexpro after tax rate of return (in hundredths)	12.40%
Percentage of Wexpro retention (in hundredths)	46.00%