CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Current Assets
Cash and cash equivalents	$ 25.0	$ 32.0
Accounts receivable, net	106.7	89.6
Unbilled gas accounts receivable	91.3	93.7
Federal income taxes receivable	61.3	28.5
Inventories, at lower of average cost or market:
Gas stored underground	45.1	43.7
Materials and supplies	28.4	30.4
Current regulatory assets	70.0	79.6
Prepaid expenses and other	12.3	11.2
Total Current Assets	440.1	408.7
Property, Plant and Equipment
Distribution property, plant and equipment	2,570.3	2,352.3
Gas and oil property, plant and equipment, successful efforts method	1,654.4	1,688.4
Transportation property, plant and equipment	1,851.1	1,827.7
Other property, plant and equipment	106.2	93.1
Total Property, Plant and Equipment	6,182.0	5,961.5
Distribution accumulated depreciation and amortization	(812.2)	(780.3)
Cost-of-service gas and oil accumulated depreciation, depletion and amortization	(789.9)	(757.3)
Transportation accumulated depreciation and amortization	(709.7)	(673.9)
Other accumulated depreciation and amortization	(21.5)	(14.5)
Total accumulated depreciation, depletion and amortization	(2,333.3)	(2,226.0)
Net Property, Plant and Equipment	3,848.7	3,735.5
Investment in unconsolidated affiliate	23.9	24.7
Other Assets
Goodwill	9.8	9.8
Noncurrent regulatory assets	14.9	25.0
Other noncurrent assets	40.4	40.2
Total Other Assets	65.1	75.0
TOTAL ASSETS	4,377.8	4,243.9
Current Liabilities
Short-term debt	457.6	347.0
Accounts payable	113.7	116.0
Accrued expenses and other	39.1	42.3
Production and other taxes	26.1	35.5
Customer advances	34.3	29.4
Current regulatory liabilities	6.4	13.4
Interest payable	11.6	11.7
Current portion of long-term debt	250.2	25.1
Current portion of capital lease obligation	1.2	1.0
Total Current Liabilities	940.2	621.4
Long-term debt, less current portion	968.1	1,220.1
Capital lease obligation, less current portion	36.0	37.4
Deferred income taxes	779.5	709.8
Asset retirement obligations	67.6	69.3
Defined benefit pension plan	81.1	141.9
Other postretirement benefits	41.9	43.8
Noncurrent regulatory liabilities	75.6	69.9
Customer contributions in aid of construction	23.7	29.2
Other noncurrent liabilities	$ 49.0	$ 54.9
Commitments and contingencies - Note 10
COMMON SHAREHOLDERS' EQUITY
Common stock	$ 469.0	$ 476.8
Retained earnings	1,031.4	970.7
Accumulated other comprehensive loss	(185.3)	(201.3)
Total Common Shareholders' Equity	1,315.1	1,246.2
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	4,377.8	4,243.9
Questar Gas [Member]
Current Assets
Cash and cash equivalents	10.5	19.8
Accounts receivable, net	77.8	66.4
Unbilled gas accounts receivable	91.0	93.7
Accounts receivable from affiliates	69.2	45.2
Federal income taxes receivable	34.2	0.0
Inventories, at lower of average cost or market:
Gas stored underground	43.9	40.3
Materials and supplies	17.1	19.2
Current regulatory assets	69.8	78.3
Prepaid expenses and other	3.5	3.5
Total Current Assets	417.0	366.4
Property, Plant and Equipment
Distribution property, plant and equipment	2,186.9	1,991.6
Other property, plant and equipment	320.9	306.3
Construction work in progress	62.5	54.4
Total Property, Plant and Equipment	2,570.3	2,352.3
Total accumulated depreciation, depletion and amortization	(812.2)	(780.3)
Net Property, Plant and Equipment	1,758.1	1,572.0
Other Assets
Goodwill	5.6	5.6
Noncurrent regulatory assets	11.9	21.3
Other noncurrent assets	3.4	3.7
Total Other Assets	20.9	30.6
TOTAL ASSETS	2,196.0	1,969.0
Current Liabilities
Notes payable to Questar	273.3	119.3
Accounts payable	91.3	76.0
Accounts payable to affiliates	74.5	78.7
Accrued expenses and other	24.4	22.7
Dividends payable to Questar	0.0	9.0
Customer advances	34.3	29.4
Federal income taxes payable	0.0	6.4
Current regulatory liabilities	4.0	12.5
Interest payable	6.8	6.8
Deferred income taxes - current	6.0	6.3
Total Current Liabilities	508.6	360.8
Long-term debt, less current portion	534.5	534.5
Deferred income taxes	436.7	383.8
Asset retirement obligations	0.6	0.6
Noncurrent regulatory liabilities	65.6	60.9
Customer contributions in aid of construction	23.7	29.2
Other noncurrent liabilities	$ 2.2	$ 2.8
Commitments and contingencies - Note 10
COMMON SHAREHOLDERS' EQUITY
Common stock	$ 23.0	$ 23.0
Additional paid-in capital	266.8	265.4
Retained earnings	334.9	308.6
Total Common Shareholders' Equity	624.7	597.0
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	2,196.0	1,969.0
Questar Pipeline [Member]
Current Assets
Cash and cash equivalents	10.2	7.4
Notes receivable from Questar	6.0	40.1
Accounts receivable, net	21.2	17.2
Accounts receivable from affiliates	49.8	39.2
Federal income taxes receivable	8.4	0.7
Inventories, at lower of average cost or market:
Materials and supplies	7.9	10.3
Current regulatory assets	0.2	1.3
Prepaid expenses and other	4.4	4.3
Total Current Assets	108.1	120.5
Property, Plant and Equipment
Transportation property, plant and equipment	1,396.8	1,371.6
Storage	308.6	300.3
Processing	24.9	24.9
Other property, plant and equipment	86.0	82.7
Construction work in progress	34.8	48.2
Total Property, Plant and Equipment	1,851.1	1,827.7
Total accumulated depreciation, depletion and amortization	(709.7)	(673.9)
Net Property, Plant and Equipment	1,141.4	1,153.8
Investment in unconsolidated affiliate	23.9	24.7
Other Assets
Goodwill	4.2	4.2
Noncurrent regulatory assets	3.0	3.7
Noncurrent regulatory and other assets	5.5	6.6
Total Other Assets	9.7	10.8
TOTAL ASSETS	1,283.1	1,309.8
Current Liabilities
Accounts payable	7.7	9.7
Accounts payable to affiliates	15.8	5.8
Accrued expenses and other	6.4	9.9
Dividends payable to Questar	0.0	16.0
Current regulatory liabilities	2.4	0.9
Interest payable	2.0	2.1
Current portion of long-term debt	0.0	25.1
Total Current Liabilities	34.3	69.5
Long-term debt, less current portion	433.6	433.7
Deferred income taxes	249.9	239.5
Asset retirement obligations	2.3	2.3
Noncurrent regulatory liabilities	10.0	9.0
Noncurrent regulatory and other liabilities	$ 16.3	$ 15.9
Commitments and contingencies - Note 10
COMMON SHAREHOLDERS' EQUITY
Common stock	$ 6.6	$ 6.6
Additional paid-in capital	353.4	351.4
Retained earnings	211.3	215.7
Accumulated other comprehensive loss	(22.3)	(22.5)
Total Common Shareholders' Equity	549.0	551.2
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	$ 1,283.1	$ 1,309.8