CONSOLIDATED STATEMENTS OF INCOME (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
REVENUES
Questar Gas / Revenues from unaffiliated customers	$ 145.0	$ 140.1	$ 541.3	$ 558.4	$ 968.1	$ 921.9
Wexpro	7.8	8.5	20.1	18.8	46.4	37.6
Questar Pipeline / Revenues from unaffiliated customers	48.1	47.0	96.1	95.3	190.3	197.8
Other	0.4	0	0.7	0	0.9	0
Total Revenues	201.3	195.6	658.2	672.5	1,205.7	1,157.3
OPERATING EXPENSES
Cost of sales (excluding operating expenses shown separately)	(24.3)	(7.3)	123.9	192.4	217.4	243.5
Operating and maintenance	41.2	37.6	96.9	85.8	185.4	170.2
General and administrative	30.5	32.0	62.0	65.8	117.2	127.6
Retirement incentive	0	0	0	0	0	4.9
Production and other taxes	18.7	14.7	36.6	30.0	64.0	51.0
Depreciation, depletion and amortization	56.8	47.5	112.1	96.0	210.9	187.9
Abandonment and impairment	2.0	0	2.0	0	82.6	0
Total Operating Expenses	124.9	124.5	433.5	470.0	877.5	785.1
Net gain (loss) from asset sales	0.1	0.1	0.1	0.1	(0.2)	2.6
OPERATING INCOME	76.5	71.2	224.8	202.6	328.0	374.8
Interest and other income	1.2	3.1	3.0	6.1	6.8	9.1
Income from unconsolidated affiliate	0.9	1.0	1.8	1.9	3.6	3.8
Interest expense	(15.8)	(14.3)	(31.6)	(28.8)	(59.7)	(56.9)
INCOME (LOSS) BEFORE INCOME TAXES	62.8	61.0	198.0	181.8	278.7	330.8
Income taxes	(22.5)	(21.6)	(72.6)	(69.5)	(104.4)	(120.9)
NET INCOME (LOSS)	40.3	39.4	125.4	112.3	174.3	209.9
Earnings Per Common Share
Basic	$ 0.23	$ 0.22	$ 0.71	$ 0.64	$ 0.99	$ 1.20
Diluted	$ 0.23	$ 0.22	$ 0.71	$ 0.64	$ 0.99	$ 1.19
Weighted-average common shares outstanding
Used in basic calculation	175.8	175.5	175.7	175.4	175.7	175.3
Used in diluted calculation	176.1	176.3	176.1	176.2	176.1	176.1
Dividends per common share	$ 0.19	$ 0.18	$ 0.37	$ 0.35	$ 0.73	$ 0.69
Questar Gas [Member]
REVENUES
Questar Gas / Revenues from unaffiliated customers	145.0	140.1	541.3	558.4	968.1	921.9
Revenues from affiliated company	0	0.1	0	0.4	0.2	1.1
Total Revenues	145.0	140.2	541.3	558.8	968.3	923.0
OPERATING EXPENSES
Cost of natural gas sold (excluding operating expenses shown separately)	87.2	83.5	341.8	374.1	618.3	595.7
Operating and maintenance	26.3	23.5	66.1	57.2	122.0	110.4
General and administrative	12.9	13.7	26.7	26.4	52.8	53.2
Retirement incentive	0	0	0	0	0	2.4
Depreciation and amortization	13.6	12.4	26.8	24.5	52.0	48.1
Other taxes	4.8	4.9	9.9	10.1	17.8	17.1
Total Operating Expenses	144.8	138.0	471.3	492.3	862.9	826.9
Net gain (loss) from asset sales	0.1	0	0.1	0	0.1	0
OPERATING INCOME	0.3	2.2	70.1	66.5	105.5	96.1
Interest and other income	1.3	1.3	2.6	2.5	5.2	5.6
Interest expense	(7.0)	(5.6)	(14.1)	(11.4)	(25.0)	(22.2)
INCOME (LOSS) BEFORE INCOME TAXES	(5.4)	(2.1)	58.6	57.6	85.7	79.5
Income taxes	2.1	0.9	(22.3)	(21.8)	(32.4)	(29.2)
NET INCOME (LOSS)	(3.3)	(1.2)	36.3	35.8	53.3	50.3
Questar Pipeline [Member]
REVENUES
Questar Pipeline / Revenues from unaffiliated customers	48.1	47.0	96.1	95.3	190.3	197.8
Revenues from affiliated companies	17.7	17.7	37.0	37.2	76.5	74.8
Total Revenues	65.8	64.7	133.1	132.5	266.8	272.6
OPERATING EXPENSES
Operating and maintenance	7.9	7.0	16.0	14.4	34.1	32.3
General and administrative	10.8	12.1	22.3	24.5	44.5	50.0
Retirement incentive	0	0	0	0	0	0.9
Depreciation and amortization	13.6	14.1	27.2	28.2	54.5	55.5
Abandonment and impairment	0	0	0	0	80.6	0
Other taxes	2.4	2.4	4.7	4.9	9.1	9.1
Cost of sales (excluding operating expenses shown separately)	0.7	1.0	2.4	2.2	6.3	7.7
Total Operating Expenses	35.4	36.6	72.6	74.2	229.1	155.5
Net gain (loss) from asset sales	0	0	0	0	0	2.6
OPERATING INCOME	30.4	28.1	60.5	58.3	37.7	119.7
Interest and other income	0.1	0.3	0.4	0.6	1.6	0.9
Income from unconsolidated affiliate	0.9	1.0	1.8	1.9	3.6	3.8
Interest expense	(6.6)	(6.5)	(13.1)	(13.0)	(25.9)	(26.1)
INCOME (LOSS) BEFORE INCOME TAXES	24.8	22.9	49.6	47.8	17.0	98.3
Income taxes	(9.1)	(8.4)	(18.2)	(17.5)	(7.7)	(36.0)
NET INCOME (LOSS)	$ 15.7	$ 14.5	$ 31.4	$ 30.3	$ 9.3	$ 62.3