CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
Current Assets
Cash and cash equivalents	$ 0	$ 16.0	$ 0
Accounts receivable, net	72.5	123.8	86.5
Unbilled gas accounts receivable	15.4	93.4	12.4
Gas stored underground	29.6	40.0	19.5
Materials and supplies	24.6	23.7	26.0
Current regulatory assets	59.0	35.8	36.0
Prepaid expenses and other	9.6	9.5	9.8
Deferred income taxes - current	14.5	9.7	17.2
Total Current Assets	225.2	351.9	207.4
Property, Plant and Equipment	5,789.9	5,674.7	5,492.7
Accumulated depreciation, depletion and amortization	(2,158.4)	(2,071.7)	(2,039.8)
Net Property, Plant and Equipment	3,631.5	3,603.0	3,452.9
Investment in unconsolidated affiliate	25.0	25.6	25.9
Noncurrent regulatory assets	18.5	20.5	20.4
Other noncurrent assets	51.0	53.3	49.5
TOTAL ASSETS	3,951.2	4,054.3	3,756.1
Current Liabilities
Checks outstanding in excess of cash balances	0.9	0	0.5
Short-term debt	177.0	276.0	206.0
Accounts payable and accrued expenses	208.5	264.8	186.5
Current regulatory liabilities	13.6	14.1	8.0
Current portion of long-term debt and capital lease obligation	0.9	0.9	2.8
Total Current Liabilities	400.9	555.8	403.8
Long-term debt and capital lease obligation, less current portion	1,284.0	1,285.5	1,136.9
Deferred income taxes	711.0	707.2	667.4
Asset retirement obligations	69.4	67.7	62.4
Defined benefit pension plan and other postretirement benefits	78.5	113.2	264.9
Noncurrent regulatory liabilities	65.7	61.2	57.7
Customer contributions in aid of construction	30.1	29.1	26.9
Other noncurrent liabilities	42.1	35.8	34.4
COMMON SHAREHOLDERS' EQUITY
Common stock	469.4	464.5	447.7
Retained earnings	936.4	876.1	890.4
Accumulated other comprehensive (loss)	(136.3)	(141.8)	(236.4)
Total Common Shareholders' Equity	1,269.5	1,198.8	1,101.7
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	3,951.2	4,054.3	3,756.1
Questar Gas [Member]
Current Assets
Cash and cash equivalents	0	8.8	0
Notes receivable from Questar	3.0	0	0
Accounts receivable, net	45.5	88.9	49.5
Unbilled gas accounts receivable	15.4	93.4	12.4
Accounts receivable from affiliates	43.6	30.4	31.9
Gas stored underground	27.8	39.2	19.1
Materials and supplies	13.1	12.1	13.7
Current regulatory assets	55.1	30.2	31.0
Prepaid expenses and other	4.8	3.0	4.4
Deferred income taxes - current	2.9	2.9	5.7
Total Current Assets	211.2	308.9	167.7
Property, Plant and Equipment	2,269.0	2,203.0	2,097.8
Accumulated depreciation, depletion and amortization	(761.4)	(745.2)	(728.1)
Net Property, Plant and Equipment	1,507.6	1,457.8	1,369.7
Noncurrent regulatory assets	15.0	16.1	16.1
Goodwill	5.6	5.6	5.6
Other noncurrent assets	4.0	4.0	3.0
TOTAL ASSETS	1,743.4	1,792.4	1,562.1
Current Liabilities
Checks outstanding in excess of cash balances	4.8	0	3.4
Notes payable to Questar	0	17.7	137.3
Accounts payable and accrued expenses	91.1	139.2	73.7
Accounts payable to affiliates	65.1	67.8	55.1
Customer advances	9.2	19.8	9.0
Current regulatory liabilities	12.8	11.1	7.1
Current portion of long-term debt and capital lease obligation	0	0	2.0
Total Current Liabilities	183.0	255.6	287.6
Long-term debt and capital lease obligation, less current portion	534.5	534.5	384.5
Deferred income taxes	340.5	340.7	323.6
Noncurrent regulatory liabilities	57.1	53.0	49.6
Customer contributions in aid of construction	30.1	29.1	26.9
Other noncurrent liabilities	3.0	3.2	3.5
COMMON SHAREHOLDERS' EQUITY
Common stock	23.0	23.0	23.0
Additional paid-in capital	264.5	263.9	173.2
Retained earnings	307.7	289.4	290.2
Total Common Shareholders' Equity	595.2	576.3	486.4
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	1,743.4	1,792.4	1,562.1
Questar Pipeline [Member]
Current Assets
Cash and cash equivalents	6.3	2.7	5.7
Notes receivable from Questar	53.8	29.4	34.4
Accounts receivable, net	17.5	18.5	18.6
Accounts receivable from affiliates	37.3	36.6	32.6
Materials and supplies	9.0	8.1	8.2
Current regulatory assets	3.9	5.6	5.0
Prepaid expenses and other	2.9	4.4	3.8
Deferred income taxes - current	1.8	1.8	1.6
Total Current Assets	132.5	107.1	109.9
Property, Plant and Equipment	1,801.2	1,774.3	1,868.6
Accumulated depreciation, depletion and amortization	(651.3)	(627.2)	(651.1)
Net Property, Plant and Equipment	1,149.9	1,147.1	1,217.5
Investment in unconsolidated affiliate	25.0	25.6	25.9
Goodwill	4.2	4.2	4.2
Noncurrent regulatory and other assets	6.7	7.7	7.8
TOTAL ASSETS	1,318.3	1,291.7	1,365.3
Current Liabilities
Accounts payable and accrued expenses	36.7	25.6	32.4
Accounts payable to affiliates	24.7	9.4	5.0
Current regulatory liabilities	0.8	3.0	0.9
Total Current Liabilities	62.2	38.0	38.3
Long-term debt and capital lease obligation, less current portion	458.8	458.9	458.9
Deferred income taxes	228.2	228.6	248.5
Noncurrent regulatory and other liabilities	16.2	13.9	14.3
COMMON SHAREHOLDERS' EQUITY
Common stock	6.6	6.6	6.6
Additional paid-in capital	350.5	349.5	348.5
Retained earnings	218.5	219.1	273.2
Accumulated other comprehensive (loss)	(22.7)	(22.9)	(23.0)
Total Common Shareholders' Equity	552.9	552.3	605.3
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY	$ 1,318.3	$ 1,291.7	$ 1,365.3