CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Current Assets
Cash and cash equivalents	$ 0.0	$ 32.0	$ 0.0
Accounts receivable, net	53.3	118.1	72.5
Unbilled gas accounts receivable	11.6	93.7	15.4
Gas stored underground	30.6	43.7	29.6
Materials and supplies	30.7	30.4	24.6
Current regulatory assets	57.1	79.6	59.0
Prepaid expenses and other	10.2	11.2	9.6
Deferred income taxes - current	8.3	5.8	14.5
Total Current Assets	201.8	414.5	225.2
Property, Plant and Equipment	6,057.2	5,961.5	5,789.9
Accumulated depreciation, depletion and amortization	(2,272.5)	(2,226.0)	(2,158.4)
Net Property, Plant and Equipment	3,784.7	3,735.5	3,631.5
Investment in unconsolidated affiliate	24.3	24.7	25.0
Noncurrent regulatory assets	23.7	25.0	18.5
Other noncurrent assets	50.4	50.0	51.0
TOTAL ASSETS	4,084.9	4,249.7	3,951.2
Current Liabilities
Checks outstanding in excess of cash balances	2.5	0.0	0.9
Short-term debt	228.0	347.0	177.0
Accounts payable, accrued expenses and other	201.0	234.9	208.5
Current regulatory liabilities	2.6	13.4	13.6
Current portion of long-term debt and capital lease obligation	277.3	26.1	0.9
Total Current Liabilities	711.4	621.4	400.9
Long-term debt and capital lease obligation, less current portion	1,004.8	1,257.5	1,284.0
Deferred income taxes	715.6	715.6	711.0
Asset retirement obligations	70.6	69.3	69.4
Defined benefit pension plan and other postretirement benefits	125.1	185.7	78.5
Noncurrent regulatory liabilities	74.9	69.9	65.7
Customer contributions in aid of construction	27.4	29.2	30.1
Other noncurrent liabilities	46.3	54.9	42.1
COMMON SHAREHOLDERS' EQUITY
Common stock	480.8	476.8	469.4
Retained earnings	1,021.8	970.7	936.4
Accumulated other comprehensive (loss)	(193.8)	(201.3)	(136.3)
Total Common Shareholders' Equity	1,308.8	1,246.2	1,269.5
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	4,084.9	4,249.7	3,951.2
Questar Gas [Member]
Current Assets
Cash and cash equivalents	0.0	19.8	0.0
Notes receivable from Questar	0.0	0.0	3.0
Accounts receivable, net	29.6	66.4	45.5
Unbilled gas accounts receivable	11.6	93.7	15.4
Accounts receivable from affiliates	68.3	45.2	43.6
Gas stored underground	26.1	40.3	27.8
Materials and supplies	18.7	19.2	13.1
Current regulatory assets	56.3	78.3	55.1
Prepaid expenses and other	3.8	3.5	4.8
Deferred income taxes - current	0.0	0.0	2.9
Total Current Assets	214.4	366.4	211.2
Property, Plant and Equipment	2,455.4	2,352.3	2,269.0
Accumulated depreciation, depletion and amortization	(799.9)	(780.3)	(761.4)
Net Property, Plant and Equipment	1,655.5	1,572.0	1,507.6
Noncurrent regulatory assets	19.8	21.3	15.0
Other noncurrent assets	9.2	9.3	9.6
TOTAL ASSETS	1,898.9	1,969.0	1,743.4
Current Liabilities
Checks outstanding in excess of cash balances	4.1	0.0	4.8
Notes payable to Questar	59.7	119.3	0.0
Accounts payable, accrued expenses and other	106.7	111.9	91.1
Accounts payable to affiliates	77.8	78.7	65.1
Dividends payable to Questar	0.0	9.0	0.0
Customer advances	18.0	29.4	9.2
Current regulatory liabilities	1.0	12.5	12.8
Deferred income taxes - current	3.9	6.3	0.0
Total Current Liabilities	271.2	367.1	183.0
Long-term debt and capital lease obligation, less current portion	534.5	534.5	534.5
Deferred income taxes	378.1	377.5	340.5
Noncurrent regulatory liabilities	65.5	60.9	57.1
Customer contributions in aid of construction	27.4	29.2	30.1
Other noncurrent liabilities	2.5	2.8	3.0
COMMON SHAREHOLDERS' EQUITY
Common stock	23.0	23.0	23.0
Additional paid-in capital	266.1	265.4	264.5
Retained earnings	330.6	308.6	307.7
Total Common Shareholders' Equity	619.7	597.0	595.2
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	1,898.9	1,969.0	1,743.4
Questar Pipeline [Member]
Current Assets
Cash and cash equivalents	1.0	7.4	6.3
Notes receivable from Questar	34.0	40.1	53.8
Accounts receivable, net	17.0	17.9	17.5
Accounts receivable from affiliates	47.1	39.2	37.3
Gas stored underground	4.5	3.4	1.8
Materials and supplies	7.4	6.9	7.2
Current regulatory assets	0.8	1.3	3.9
Prepaid expenses and other	2.8	4.3	2.9
Deferred income taxes - current	2.1	1.9	1.8
Total Current Assets	116.7	122.4	132.5
Property, Plant and Equipment	1,843.6	1,827.7	1,801.2
Accumulated depreciation, depletion and amortization	(697.8)	(673.9)	(651.3)
Net Property, Plant and Equipment	1,145.8	1,153.8	1,149.9
Investment in unconsolidated affiliate	24.3	24.7	25.0
Noncurrent regulatory and other assets	10.7	10.8	10.9
TOTAL ASSETS	1,297.5	1,311.7	1,318.3
Current Liabilities
Accounts payable, accrued expenses and other	21.8	21.7	36.7
Accounts payable to affiliates	9.1	5.8	24.7
Dividends payable to Questar	0.0	16.0	0.0
Current regulatory liabilities	1.6	0.9	0.8
Current portion of long-term debt and capital lease obligation	25.1	25.1	0.0
Total Current Liabilities	57.6	69.5	62.2
Long-term debt and capital lease obligation, less current portion	433.6	433.7	458.8
Deferred income taxes	240.7	241.4	228.2
Noncurrent regulatory and other liabilities	16.0	15.9	16.2
COMMON SHAREHOLDERS' EQUITY
Common stock	6.6	6.6	6.6
Additional paid-in capital	352.7	351.4	350.5
Retained earnings	212.8	215.7	218.5
Accumulated other comprehensive (loss)	(22.5)	(22.5)	(22.7)
Total Common Shareholders' Equity	549.6	551.2	552.9
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	$ 1,297.5	$ 1,311.7	$ 1,318.3