CONSOLIDATED STATEMENTS OF INCOME (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
REVENUES
Questar Gas / Revenues from unaffiliated customers	$ 965.5	$ 901.8	$ 918.9
Questar Pipeline / Revenues from unaffiliated customers	197.4	197.2	173.2
Wexpro	31.5	24.6	17.8
Total Revenues	1,194.4	1,123.6	1,109.9
OPERATING EXPENSES
Cost of sales (excluding operating expenses shown separately)	321.5	280.9	331.4
Cost of natural gas sold
Operating and maintenance	175.9	175.8	167.6
General and administrative	117.9	108.5	93.4
Separation costs	0	11.5	0
Depreciation, depletion and amortization	159.9	153.4	147.1
Other taxes	52.5	50.6	42.4
Total Operating Expenses	827.7	780.7	781.9
Net gain from asset sales	0.2	0.4	0.2
Operating Income (loss)	366.9	343.3	328.2
Interest and other income	10.4	11.7	12.5
Income from unconsolidated affiliate	3.8	3.8	3.8
Interest expense	(56.8)	(57.1)	(59.6)
Income From Continuing Operations Before Income Taxes	324.3	301.7	284.9
Income taxes	(116.4)	(109.4)	(104.4)
Income from Continuing Operations	207.9	192.3	180.5
Discontinued operations, net of income taxes	0	148.2	215.4
Discontinued operations, noncontrolling interest	0	(1.3)	(2.6)
Total Discontinued Operations, Net Of Income Taxes	0	146.9	212.8
NET INCOME ATTRIBUTABLE TO QUESTAR	207.9	339.2	393.3
Earnings Per Common Share Attributable To Questar
Basic from continuing operations	$ 1.17	$ 1.09	$ 1.03
Basic from discontinued operations	$ 0.00	$ 0.84	$ 1.23
Basic total	$ 1.17	$ 1.93	$ 2.26
Diluted from continuing operations	$ 1.16	$ 1.08	$ 1.02
Diluted from discontinued operations	$ 0.00	$ 0.83	$ 1.21
Diluted total	$ 1.16	$ 1.91	$ 2.23
Weighted average common shares outstanding
Used in basic calculation	177.4	175.4	174.1
Used in diluted calculation	178.8	178.0	176.3
Questar Pipeline [Member]
REVENUES
Questar Pipeline / Revenues from unaffiliated customers	197.4	197.2	173.2
Revenues from affiliated companies	74.4	74.0	72.2
Total Revenues	271.8	271.2	245.4
Cost of natural gas sold
Operating and maintenance	35.3	41.4	40.1
General and administrative	46.5	41.0	36.1
Depreciation and amortization	51.2	47.4	44.3
Other taxes	10.1	9.0	8.6
Cost of Goods and Services Sold (excluding operating expenses shown separately	3.1	2.4	1.6
Total Operating Expenses	146.2	141.2	130.7
Net gain from asset sales	0.3	0.8	0.5
Operating Income (loss)	125.9	130.8	115.2
Interest and other income	0.9	0.4	2.5
Income from unconsolidated affiliate	3.8	3.8	3.8
Interest expense	(24.5)	(28.8)	(29.5)
Income From Continuing Operations Before Income Taxes	106.1	106.2	92.0
Income taxes	(38.2)	(38.8)	(33.8)
NET INCOME ATTRIBUTABLE TO QUESTAR	67.9	67.4	58.2
Questar Gas [Member]
REVENUES
Questar Gas / Revenues from unaffiliated customers	965.5	901.8	918.9
Revenues from affiliated company	3.3	1.1	1.0
Total Revenues	968.8	902.9	919.9
Cost of natural gas sold
Cost of natural gas sold / Unaffiliated parties	318.4	278.5	329.8
Cost of natural gas sold / Affiliated companies	327.3	313.7	296.8
Cost of natural gas sold (excluding operating expenses shown separately)	645.7	592.2	626.6
Operating and maintenance	118.5	114.4	106.4
General and administrative	51.0	49.9	42.9
Depreciation and amortization	44.5	43.7	43.8
Other taxes	15.0	14.1	13.3
Total Operating Expenses	874.7	814.3	833.0
Operating Income (loss)	94.1	88.6	86.9
Interest and other income	5.4	6.7	7.6
Interest expense	(25.9)	(26.2)	(28.5)
Income From Continuing Operations Before Income Taxes	73.6	69.1	66.0
Income taxes	(27.5)	(25.2)	(24.4)
NET INCOME ATTRIBUTABLE TO QUESTAR	$ 46.1	$ 43.9	$ 41.6