XML 34 R32.htm IDEA: XBRL DOCUMENT v2.4.0.8
Fair Value Measurements (Details) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2014
Dec. 31, 2013
Mar. 31, 2013
Carrying Amount [Member]
     
Financial assets [Abstract]      
Cash and cash equivalents $ 5.6 $ 16.0 $ 7.2
Long-term investment 15.3 17.3 16.1
Financial liabilities [Abstract]      
Short-term debt 157.0 276.0 202.0
Long-term debt, including current portion 1,246.6 1,247.1 1,100.5
Estimated Fair Value [Member] | Fair Value, Inputs, Level 1 [Member]
     
Financial assets [Abstract]      
Cash and cash equivalents 5.6 16.0 7.2
Financial liabilities [Abstract]      
Short-term debt 157.0 276.0 202.0
Estimated Fair Value [Member] | Fair Value, Inputs, Level 2 [Member]
     
Financial liabilities [Abstract]      
Long-term debt, including current portion 1,357.5 1,310.8 1,260.1
Estimated Fair Value [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
     
Financial assets [Abstract]      
Long-term investment 15.3 17.3 16.1
Questar Gas [Member] | Carrying Amount [Member]
     
Financial assets [Abstract]      
Cash and cash equivalents 1.4 8.8 2.8
Notes receivable from Questar 30.6 0 0
Financial liabilities [Abstract]      
Notes payable to Questar 0 17.7 132.3
Long-term debt, including current portion 534.5 534.5 386.5
Questar Gas [Member] | Estimated Fair Value [Member] | Fair Value, Inputs, Level 1 [Member]
     
Financial assets [Abstract]      
Cash and cash equivalents 1.4 8.8 2.8
Notes receivable from Questar 30.6 0 0
Financial liabilities [Abstract]      
Notes payable to Questar 0 17.7 132.3
Questar Gas [Member] | Estimated Fair Value [Member] | Fair Value, Inputs, Level 2 [Member]
     
Financial liabilities [Abstract]      
Long-term debt, including current portion 588.9 568.0 460.0
Questar Pipeline [Member] | Carrying Amount [Member]
     
Financial assets [Abstract]      
Cash and cash equivalents 4.9 2.7 5.4
Notes receivable from Questar 46.6 29.4 33.1
Financial liabilities [Abstract]      
Long-term debt, including current portion 458.8 458.9 458.9
Questar Pipeline [Member] | Estimated Fair Value [Member] | Fair Value, Inputs, Level 1 [Member]
     
Financial assets [Abstract]      
Cash and cash equivalents 4.9 2.7 5.4
Notes receivable from Questar 46.6 29.4 33.1
Questar Pipeline [Member] | Estimated Fair Value [Member] | Fair Value, Inputs, Level 2 [Member]
     
Financial liabilities [Abstract]      
Long-term debt, including current portion $ 509.4 $ 486.0 $ 537.3