CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010
Current Assets
Cash and cash equivalents	$ 0	$ 21.8	$ 0
Federal income taxes receivable	0	37.1	0
Accounts receivable, net	85.1	122.1	82.8
Unbilled gas accounts receivable	15.0	81.6	15.3
Gas stored underground	18.7	43.7	20.7
Materials and supplies	21.5	19.0	19.8
Current regulatory assets	33.2	53.5	62.1
Prepaid expenses and other	9.0	9.0	8.0
Deferred income taxes - current	14.8	11.8	14.3
Total Current Assets	197.3	399.6	223.0
Property, Plant and Equipment	4,759.8	4,642.8	4,456.1
Accumulated depreciation, depletion and amortization	(1,825.5)	(1,758.2)	(1,689.6)
Net Property, Plant and Equipment	2,934.3	2,884.6	2,766.5
Investment in unconsolidated affiliate	27.4	27.9	28.2
Noncurrent regulatory assets	20.5	21.7	21.7
Other noncurrent assets	41.9	39.8	37.9
TOTAL ASSETS	3,221.4	3,373.6	3,077.3
Current Liabilities
Checks outstanding in excess of cash balances	4.5	0	5.8
Short-term debt	137.0	242.0	345.0
Accounts payable and accrued expenses	136.0	225.1	198.3
Current regulatory liabilities	24.8	6.0	7.2
Current portion of long-term debt	82.0	182.0	100.0
Total Current Liabilities	384.3	655.1	656.3
Long-term debt, less current portion	901.8	898.5	731.1
Deferred income taxes	536.5	474.7	396.4
Asset retirement obligations	65.2	60.9	58.3
Defined benefit pension plan and other postretirement benefits	149.5	169.5	179.2
Customer contributions-in-aid-of-construction	45.8	45.5	51.3
Regulatory and other noncurrent liabilities	32.2	33.3	33.9
COMMON SHAREHOLDERS' EQUITY
Common stock	506.4	493.0	474.5
Retained earnings	703.2	647.1	597.7
Accumulated other comprehensive (loss)	(103.5)	(104.0)	(101.4)
Total Common Shareholders' Equity	1,106.1	1,036.1	970.8
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	3,221.4	3,373.6	3,077.3
Questar Pipeline [Member]
Current Assets
Cash and cash equivalents	0.2	5.3	0.5
Notes receivable from Questar	0	30.3	49.5
Accounts receivable, net	19.2	20.2	16.8
Accounts receivable from affiliates	19.6	16.2	15.1
Materials and supplies	7.0	7.2	7.2
Prepaid expenses and other	4.1	5.2	4.7
Deferred income taxes - current	1.2	1.2	0.7
Total Current Assets	51.3	85.6	94.5
Property, Plant and Equipment	1,739.4	1,711.1	1,633.2
Accumulated depreciation, depletion and amortization	(569.2)	(545.0)	(525.5)
Net Property, Plant and Equipment	1,170.2	1,166.1	1,107.7
Investment in unconsolidated affiliate	27.4	27.9	28.2
Goodwill	4.2	4.2	4.2
Regulatory and other noncurrent assets	8.3	9.6	10.4
TOTAL ASSETS	1,261.4	1,293.4	1,245.0
Current Liabilities
Notes payable to Questar	49.3	0	0
Accounts payable and accrued expenses	25.7	42.4	29.0
Accounts payable to affiliates	2.8	4.7	2.9
Current regulatory liabilities	3.5	3.2	4.8
Current portion of long-term debt	80.0	180.0	100.0
Total Current Liabilities	161.3	230.3	136.7
Long-term debt, less current portion	281.0	280.9	361.1
Deferred income taxes	198.8	180.1	165.5
Regulatory and other noncurrent liabilities	15.6	15.3	15.4
COMMON SHAREHOLDERS' EQUITY
Common stock	6.6	6.6	6.6
Additional paid-in capital	344.9	344.0	343.3
Retained earnings	252.7	236.2	216.4
Accumulated other comprehensive (loss)	0.5	0	0
Total Common Shareholders' Equity	604.7	586.8	566.3
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	1,261.4	1,293.4	1,245.0
Questar Gas [Member]
Current Assets
Cash and cash equivalents	0	4.7	0
Accounts receivable, net	50.3	93.0	47.6
Unbilled gas accounts receivable	14.7	81.5	15.2
Accounts receivable from affiliates	1.8	4.5	2.3
Gas stored underground	18.7	43.3	19.2
Materials and supplies	10.3	7.9	8.3
Current regulatory assets	33.1	52.7	61.0
Prepaid expenses and other	3.3	2.9	2.4
Deferred income taxes - current	4.3	1.3	3.6
Total Current Assets	136.5	291.8	159.6
Property, Plant and Equipment	1,856.1	1,817.6	1,760.7
Accumulated depreciation, depletion and amortization	(734.9)	(721.3)	(702.8)
Net Property, Plant and Equipment	1,121.2	1,096.3	1,057.9
Noncurrent regulatory assets	14.8	15.0	15.2
Goodwill	5.6	5.6	5.6
Other noncurrent assets	2.4	2.6	6.7
TOTAL ASSETS	1,280.5	1,411.3	1,245.0
Current Liabilities
Checks outstanding in excess of cash balances	2.9	0	4.1
Notes payable to Questar	44.0	153.6	53.9
Accounts payable and accrued expenses	56.7	108.3	81.8
Accounts payable to affiliates	36.2	53.6	50.5
Customer advances	9.7	26.2	10.3
Current regulatory liabilities	21.3	2.8	2.4
Current portion of long-term debt	2.0	2.0	0
Total Current Liabilities	172.8	346.5	203.0
Long-term debt, less current portion	368.0	368.0	370.0
Deferred income taxes	253.7	230.3	198.4
Customer contributions-in-aid-of-construction	45.8	45.5	51.3
Regulatory and other noncurrent liabilities	5.5	5.5	6.0
COMMON SHAREHOLDERS' EQUITY
Common stock	23.0	23.0	23.0
Additional paid-in capital	150.9	150.3	149.7
Retained earnings	260.8	242.2	243.6
Total Common Shareholders' Equity	434.7	415.5	416.3
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	$ 1,280.5	$ 1,411.3	$ 1,245.0