CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010
Current Assets
Cash and cash equivalents	$ 0	$ 21.8	$ 0
Federal income taxes receivable	5.0	37.1	22.7
Accounts receivable, net	69.8	122.1	56.3
Unbilled gas accounts receivable	12.6	81.6	13.9
Gas stored underground	49.6	43.7	53.9
Materials and supplies	24.4	19.0	18.7
Current regulatory assets	38.3	53.5	84.6
Prepaid expenses and other	6.1	9.0	8.5
Deferred income taxes - current	14.4	11.8	14.3
Total Current Assets	220.2	399.6	272.9
Property, Plant and Equipment	4,869.4	4,642.8	4,531.9
Accumulated depreciation, depletion and amortization	(1,858.4)	(1,758.2)	(1,726.0)
Net Property, Plant and Equipment	3,011.0	2,884.6	2,805.9
Investment in unconsolidated affiliate	27.6	27.9	28.2
Noncurrent regulatory assets	21.9	21.7	22.3
Other noncurrent assets	47.7	39.8	37.8
TOTAL ASSETS	3,328.4	3,373.6	3,167.1
Current Liabilities
Checks outstanding in excess of cash balances	9.6	0	5.4
Short-term debt	278.0	242.0	395.0
Accounts payable and accrued expenses	206.8	225.1	187.0
Current regulatory liabilities	3.2	6.0	6.0
Current portion of long-term debt	25.0	182.0	182.0
Total Current Liabilities	522.6	655.1	775.4
Long-term debt, less current portion	881.4	898.5	649.1
Deferred income taxes	548.5	474.7	418.9
Asset retirement obligations	64.5	60.9	59.4
Defined benefit pension plan and other postretirement benefits	148.2	169.5	201.4
Customer contributions-in-aid-of-construction	33.8	45.5	51.3
Regulatory and other noncurrent liabilities	35.4	33.3	37.2
COMMON SHAREHOLDERS' EQUITY
Common stock	508.6	493.0	482.2
Retained earnings	712.2	647.1	617.1
Accumulated other comprehensive (loss)	(126.8)	(104.0)	(124.9)
Total Common Shareholders' Equity	1,094.0	1,036.1	974.4
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	3,328.4	3,373.6	3,167.1
Questar Pipeline [Member]
Current Assets
Cash and cash equivalents	0.4	5.3	0
Note receivable from Questar	0	30.3	66.5
Accounts receivable, net	18.8	20.2	19.6
Accounts receivable from affiliates	19.8	16.2	15.0
Materials and supplies	7.2	7.2	7.3
Prepaid expenses and other	2.0	5.2	3.8
Deferred income taxes - current	1.1	1.2	0.7
Total Current Assets	49.3	85.6	112.9
Property, Plant and Equipment	1,780.1	1,711.1	1,658.1
Accumulated depreciation, depletion and amortization	(579.5)	(545.0)	(536.5)
Net Property, Plant and Equipment	1,200.6	1,166.1	1,121.6
Investment in unconsolidated affiliate	27.6	27.9	28.2
Goodwill	4.2	4.2	4.2
Regulatory and other noncurrent assets	9.0	9.6	10.8
TOTAL ASSETS	1,290.7	1,293.4	1,277.7
Current Liabilities
Checks outstanding in excess of cash balances	0	0	0.1
Notes payable to Questar	130.3	0	0
Accounts payable and accrued expenses	70.0	42.4	47.8
Accounts payable to affiliates	3.0	4.7	5.9
Current regulatory liabilities	1.9	3.2	4.0
Current portion of long-term debt	0	180.0	180.0
Total Current Liabilities	205.2	230.3	237.8
Long-term debt, less current portion	280.9	280.9	281.1
Deferred income taxes	195.9	180.1	166.9
Regulatory and other noncurrent liabilities	15.9	15.3	15.7
COMMON SHAREHOLDERS' EQUITY
Common stock	6.6	6.6	6.6
Additional paid-in capital	345.3	344.0	344.2
Retained earnings	263.7	236.2	225.4
Accumulated other comprehensive (loss)	(22.8)	0	0
Total Common Shareholders' Equity	592.8	586.8	576.2
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	1,290.7	1,293.4	1,277.7
Questar Gas [Member]
Current Assets
Cash and cash equivalents	0	4.7	0
Federal income taxes receivable	0	7.7	14.4
Accounts receivable, net	24.1	85.3	25.2
Unbilled gas accounts receivable	12.3	81.5	13.8
Accounts receivable from affiliates	2.4	4.5	3.3
Gas stored underground	49.6	43.3	52.5
Materials and supplies	12.2	7.9	8.2
Current regulatory assets	38.2	52.7	83.5
Prepaid expenses and other	2.5	2.9	3.6
Deferred income taxes - current	3.9	1.3	3.6
Total Current Assets	145.2	291.8	208.1
Property, Plant and Equipment	1,879.3	1,817.6	1,786.3
Accumulated depreciation, depletion and amortization	(742.2)	(721.3)	(713.3)
Net Property, Plant and Equipment	1,137.1	1,096.3	1,073.0
Noncurrent regulatory assets	15.5	15.0	15.1
Goodwill	5.6	5.6	5.6
Other noncurrent assets	2.4	2.6	6.8
TOTAL ASSETS	1,305.8	1,411.3	1,308.6
Current Liabilities
Checks outstanding in excess of cash balances	3.2	0	2.2
Notes payable to Questar	97.9	153.6	97.0
Accounts payable and accrued expenses	63.6	108.3	71.0
Accounts payable to affiliates	38.6	53.6	54.6
Customer advances	23.8	26.2	25.9
Current regulatory liabilities	1.3	2.8	2.0
Current portion of long-term debt	25.0	2.0	2.0
Total Current Liabilities	253.4	346.5	254.7
Long-term debt, less current portion	343.0	368.0	368.0
Deferred income taxes	250.9	230.3	227.9
Customer contributions-in-aid-of-construction	33.8	45.5	51.3
Regulatory and other noncurrent liabilities	5.2	5.5	6.0
COMMON SHAREHOLDERS' EQUITY
Common stock	23.0	23.0	23.0
Additional paid-in capital	151.1	150.3	150.4
Retained earnings	245.4	242.2	227.3
Total Common Shareholders' Equity	419.5	415.5	400.7
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	$ 1,305.8	$ 1,411.3	$ 1,308.6