CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Current Assets
Cash and cash equivalents	$ 7.3	$ 16.0	$ 0
Accounts receivable, net	57.3	123.8	58.0
Unbilled gas accounts receivable	12.8	93.4	11.7
Gas stored underground	69.3	40.0	59.4
Materials and supplies	25.2	23.7	24.0
Current regulatory assets	84.2	35.8	49.3
Prepaid expenses and other	6.3	9.5	6.0
Deferred income taxes - current	14.7	9.7	8.8
Total Current Assets	277.1	351.9	217.2
Property, Plant and Equipment	5,852.3	5,674.7	5,583.8
Accumulated depreciation, depletion and amortization	(2,185.2)	(2,071.7)	(2,037.9)
Net Property, Plant and Equipment	3,667.1	3,603.0	3,545.9
Investment in unconsolidated affiliate	24.9	25.6	25.8
Noncurrent regulatory assets	18.6	20.5	21.3
Other noncurrent assets	50.2	53.3	50.9
TOTAL ASSETS	4,037.9	4,054.3	3,861.1
Current Liabilities
Checks outstanding in excess of cash balances	0	0	1.6
Short-term debt	234.0	276.0	355.0
Accounts payable and accrued expenses	225.4	264.8	211.6
Current regulatory liabilities	11.0	14.1	1.8
Current portion of long-term debt and capital lease obligation	1.0	0.9	0.8
Total Current Liabilities	471.4	555.8	570.8
Long-term debt and capital lease obligation, less current portion	1,283.3	1,285.5	1,136.1
Deferred income taxes	718.5	707.2	645.9
Asset retirement obligations	69.2	67.7	65.9
Defined benefit pension plan and other postretirement benefits	73.3	113.2	257.3
Noncurrent regulatory liabilities	67.9	61.2	59.5
Customer contributions in aid of construction	29.6	29.1	31.5
Other noncurrent liabilities	45.4	35.8	35.5
COMMON SHAREHOLDERS' EQUITY
Common stock	471.5	464.5	449.7
Retained earnings	941.6	876.1	839.6
Accumulated other comprehensive (loss)	(133.8)	(141.8)	(230.7)
Total Common Shareholders' Equity	1,279.3	1,198.8	1,058.6
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	4,037.9	4,054.3	3,861.1
Questar Gas [Member]
Current Assets
Cash and cash equivalents	0	8.8	0
Accounts receivable, net	27.6	88.9	24.2
Unbilled gas accounts receivable	12.8	93.4	11.7
Accounts receivable from affiliates	44.7	30.4	31.4
Gas stored underground	66.8	39.2	56.5
Materials and supplies	14.0	12.1	12.2
Current regulatory assets	82.6	30.2	45.5
Prepaid expenses and other	2.6	3.0	2.4
Deferred income taxes - current	3.0	2.9	1.5
Total Current Assets	254.1	308.9	185.4
Property, Plant and Equipment	2,315.1	2,203.0	2,147.8
Accumulated depreciation, depletion and amortization	(770.4)	(745.2)	(739.4)
Net Property, Plant and Equipment	1,544.7	1,457.8	1,408.4
Noncurrent regulatory assets	14.4	16.1	16.5
Goodwill	5.6	5.6	5.6
Other noncurrent assets	3.7	4.0	3.0
TOTAL ASSETS	1,822.5	1,792.4	1,618.9
Current Liabilities
Checks outstanding in excess of cash balances	2.1	0	1.4
Notes payable to Questar	90.8	17.7	195.0
Accounts payable and accrued expenses	91.8	139.2	80.3
Accounts payable to affiliates	52.2	67.8	49.9
Customer advances	23.2	19.8	21.9
Current regulatory liabilities	10.4	11.1	0.5
Total Current Liabilities	270.5	255.6	349.0
Long-term debt and capital lease obligation, less current portion	534.5	534.5	384.5
Deferred income taxes	348.5	340.7	330.7
Noncurrent regulatory liabilities	59.1	53.0	51.3
Customer contributions in aid of construction	29.6	29.1	31.5
Other noncurrent liabilities	2.8	3.2	3.0
COMMON SHAREHOLDERS' EQUITY
Common stock	23.0	23.0	23.0
Additional paid-in capital	264.9	263.9	173.6
Retained earnings	289.6	289.4	272.3
Total Common Shareholders' Equity	577.5	576.3	468.9
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	1,822.5	1,792.4	1,618.9
Questar Pipeline [Member]
Current Assets
Cash and cash equivalents	0.4	2.7	1.5
Notes receivable from Questar	35.2	29.4	36.6
Accounts receivable, net	17.3	18.5	17.8
Accounts receivable from affiliates	37.8	36.6	32.7
Gas stored underground	2.5	0.8	2.9
Materials and supplies	6.9	7.3	7.5
Current regulatory assets	1.6	5.6	3.8
Prepaid expenses and other	1.7	4.4	1.8
Deferred income taxes - current	1.8	1.8	1.6
Total Current Assets	105.2	107.1	106.2
Property, Plant and Equipment	1,824.0	1,774.3	1,766.1
Accumulated depreciation, depletion and amortization	(662.9)	(627.2)	(617.8)
Net Property, Plant and Equipment	1,161.1	1,147.1	1,148.3
Investment in unconsolidated affiliate	24.9	25.6	25.8
Goodwill	4.2	4.2	4.2
Noncurrent regulatory and other assets	7.2	7.7	8.2
TOTAL ASSETS	1,302.6	1,291.7	1,292.7
Current Liabilities
Accounts payable and accrued expenses	41.1	25.6	35.9
Accounts payable to affiliates	3.6	9.4	3.7
Current regulatory liabilities	0.6	3.0	1.3
Total Current Liabilities	45.3	38.0	40.9
Long-term debt and capital lease obligation, less current portion	458.8	458.9	458.8
Deferred income taxes	230.0	228.6	226.9
Noncurrent regulatory and other liabilities	16.1	13.9	13.9
COMMON SHAREHOLDERS' EQUITY
Common stock	6.6	6.6	6.6
Additional paid-in capital	351.0	349.5	349.2
Retained earnings	217.4	219.1	219.3
Accumulated other comprehensive (loss)	(22.6)	(22.9)	(22.9)
Total Common Shareholders' Equity	552.4	552.3	552.2
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	$ 1,302.6	$ 1,291.7	$ 1,292.7