Asset Impairments (Notes)	3 Months Ended
Mar. 31, 2015
Strategic Review of Questar Southern Trails Pipeline and Impairment of Eastern Segment [Abstract]
Asset Impairments	Note 11 - Asset Impairments During the second quarter of 2014, Wexpro recorded a pre-tax abandonment and impairment charge of $2.0 million for its share of the remaining investment in the Brady field. Wexpro concluded that the field had reached the end of its productive life because it was no longer economical to produce natural gas and oil. During the third quarter of 2013, Questar Pipeline updated its five-year forecast for the eastern segment of Southern Trails Pipeline, which resulted in revised projections of higher operating expenses, including right-of-way and pipeline safety costs. Current and projected market rates for natural gas transportation between the San Juan Basin and California markets did not cover these increasing operating expenses. Because of changes in expected cash flows in the third quarter of 2013 and the lack of progress in selling or recontracting this pipeline, Questar Pipeline recorded a noncash impairment of its entire investment in the eastern segment of Southern Trails Pipeline of $80.6 million, or $52.4 million after income taxes. Questar Pipeline used a probability-weighted discounted cash flow analysis that included significant inputs such as Questar Pipeline's cost of capital and assumptions regarding future transportation rates and operating costs.

Note 11 - Asset Impairments

During the second quarter of 2014, Wexpro recorded a pre-tax abandonment and impairment charge of $2.0 million for its share of the remaining investment in the Brady field. Wexpro concluded that the field had reached the end of its productive life because it was no longer economical to produce natural gas and oil.

During the third quarter of 2013, Questar Pipeline updated its five-year forecast for the eastern segment of Southern Trails Pipeline, which resulted in revised projections of higher operating expenses, including right-of-way and pipeline safety costs. Current and projected market rates for natural gas transportation between the San Juan Basin and California markets did not cover these increasing operating expenses. Because of changes in expected cash flows in the third quarter of 2013 and the lack of progress in selling or recontracting this pipeline, Questar Pipeline recorded a noncash impairment of its entire investment in the eastern segment of Southern Trails Pipeline of $80.6 million, or $52.4 million after income taxes. Questar Pipeline used a probability-weighted discounted cash flow analysis that included significant inputs such as Questar Pipeline's cost of capital and assumptions regarding future transportation rates and operating costs.