CONSOLIDATED STATEMENTS OF INCOME (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
REVENUES
Questar Gas / Revenues from unaffiliated customers	$ 985.2	$ 859.7	$ 965.5
Wexpro	45.1	36.1	31.5
Questar Pipeline / Revenues from unaffiliated customers	189.5	203.1	197.4
Other	0.2	0	0
Total Revenues	1,220.0	1,098.9	1,194.4
OPERATING EXPENSES
Cost of sales (excluding operating expenses shown separately)	285.9	192.3	321.5
Cost of natural gas sold
Operating and maintenance	174.3	180.8	175.9
General and administrative	121.0	120.8	117.9
Retirement incentive	0	4.9	0
Production and other taxes	57.4	47.9	52.5
Depreciation, depletion and amortization	194.8	181.6	159.9
Asset impairment	80.6	0	0
Other taxes	57.4	47.9	52.5
Total Operating Expenses	914.0	728.3	827.7
Net gain (loss) from asset sales	(0.2)	5.1	0.2
OPERATING INCOME	305.8	375.7	366.9
Interest and other income	9.9	7.0	10.4
Income from unconsolidated affiliate	3.7	3.7	3.8
Interest expense	(56.9)	(57.9)	(56.8)
INCOME BEFORE INCOME TAXES	262.5	328.5	324.3
Income taxes	(101.3)	(116.5)	(116.4)
NET INCOME	161.2	212.0	207.9
Earnings Per Common Share
Basic	$ 0.92	$ 1.20	$ 1.17
Diluted	$ 0.92	$ 1.19	$ 1.16
Weighted-average common shares outstanding
Used in basic calculation	175.4	176.5	177.4
Used in diluted calculation	176.0	177.5	178.8
Questar Gas [Member]
REVENUES
Questar Gas / Revenues from unaffiliated customers	985.2	859.7	965.5
Revenues from affiliated company	0.6	2.5	3.3
Total Revenues	985.8	862.2	968.8
Cost of natural gas sold
Cost of natural gas sold / Unaffiliated parties	279.7	185.6	318.4
Cost of natural gas sold / Affiliated companies	370.9	347.7	327.3
Total cost of natural gas sold (excluding operating expenses shown separately)	650.6	533.3	645.7
Operating and maintenance	113.1	119.0	118.5
General and administrative	52.5	51.2	51.0
Retirement incentive	0	2.4	0
Depreciation and amortization	49.7	47.2	44.5
Other taxes	18.0	16.2	15.0
Total Operating Expenses	883.9	769.3	874.7
OPERATING INCOME	101.9	92.9	94.1
Interest and other income	5.1	5.5	5.4
Interest expense	(22.3)	(24.1)	(25.9)
INCOME BEFORE INCOME TAXES	84.7	74.3	73.6
Income taxes	(31.9)	(27.2)	(27.5)
NET INCOME	52.8	47.1	46.1
Questar Pipeline [Member]
REVENUES
Questar Pipeline / Revenues from unaffiliated customers	189.5	203.1	197.4
Revenues from affiliated companies	76.7	74.4	74.4
Total Revenues	266.2	277.5	271.8
Cost of natural gas sold
Operating and maintenance	32.5	35.2	35.3
General and administrative	46.7	50.0	46.5
Retirement incentive	0	0.9	0
Depreciation and amortization	55.5	54.3	51.2
Asset impairment	80.6	0	0
Other taxes	9.3	9.1	10.1
Cost of sales (excluding operating expenses shown separately)	6.1	6.7	3.1
Total Operating Expenses	230.7	156.2	146.2
Net gain (loss) from asset sales	0	2.7	0.3
OPERATING INCOME	35.5	124.0	125.9
Interest and other income	1.8	0.6	0.9
Income from unconsolidated affiliate	3.7	3.7	3.8
Interest expense	(25.8)	(26.3)	(24.5)
INCOME BEFORE INCOME TAXES	15.2	102.0	106.1
Income taxes	(7.0)	(37.3)	(38.2)
NET INCOME	$ 8.2	$ 64.7	$ 67.9