Debt Maturities of Long-term Debt (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2013
Debt Maturities [Line Items]
Number of years of long-term debt maturities	5 years
Maturities of Long-term Debt [Abstract]
2014	$ 0
2015	25.1
2016	250.0
2017	14.5
2018	375.0
Questar Corp [Member]
Maturities of Long-term Debt [Abstract]
2014	0
2015	0
2016	250.0
2017	0
2018	0
Questar Gas [Member]
Maturities of Long-term Debt [Abstract]
2014	0
2015	0
2016	0
2017	14.5
2018	120.0
Questar Pipeline [Member]
Maturities of Long-term Debt [Abstract]
2014	0
2015	25.1
2016	0
2017	0
2018	$ 255.0

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This is the number of years that are being disclosed for long-term debt maturities beginning with the current year.

+ References

No definition available.

+ Details

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- Definition

Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

+ Details

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- Definition

Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the fifth fiscal year following the latest fiscal year.

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+ Details

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- Definition

Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the fourth fiscal year following the latest fiscal year.

+ References

+ Details

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- Definition

Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the third fiscal year following the latest fiscal year.

+ References

+ Details

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- Definition

Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year.

+ References

+ Details

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