CONDENSED CONSOLIDATED BALANCE SHEETS (USD $)
In Millions, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Mar. 31, 2014
Current Assets      
Cash and cash equivalents $ 4.8 $ 32.0 $ 5.6
Accounts receivable, net 104.5 118.1 130.6
Unbilled gas accounts receivable 41.5 93.7 56.3
Gas stored underground 12.4 43.7 6.9
Materials and supplies 28.7 30.4 25.0
Current regulatory assets 43.0 79.6 29.8
Prepaid expenses and other 8.7 11.2 7.5
Deferred income taxes - current 8.2 5.8 14.5
Total Current Assets 251.8 414.5 276.2
Property, Plant and Equipment 6,033.1 5,961.5 5,723.5
Accumulated depreciation, depletion and amortization (2,277.2) (2,226.0) (2,121.6)
Net Property, Plant and Equipment 3,755.9 3,735.5 3,601.9
Investment in unconsolidated affiliate 24.5 24.7 25.2
Noncurrent regulatory assets 23.6 25.0 19.3
Other noncurrent assets 50.1 50.0 51.8
TOTAL ASSETS 4,105.9 4,249.7 3,974.4
Current Liabilities      
Short-term debt 214.0 347.0 157.0
Accounts payable and accrued expenses 200.5 234.9 229.9
Current regulatory liabilities 5.2 13.4 17.2
Current portion of long-term debt and capital lease obligation 277.8 26.1 0.9
Total Current Liabilities 697.5 621.4 405.0
Long-term debt and capital lease obligation, less current portion 1,005.1 1,257.5 1,284.7
Deferred income taxes 716.6 715.6 712.6
Asset retirement obligations 75.0 69.3 68.6
Defined benefit pension plan and other postretirement benefits 155.7 185.7 108.5
Noncurrent regulatory liabilities 72.5 69.9 63.2
Customer contributions in aid of construction 28.0 29.2 32.0
Other noncurrent liabilities 57.2 54.9 43.6
COMMON SHAREHOLDERS' EQUITY      
Common stock 477.6 476.8 465.7
Retained earnings 1,018.2 970.7 929.6
Accumulated other comprehensive (loss) (197.5) (201.3) (139.1)
Total Common Shareholders' Equity 1,298.3 1,246.2 1,256.2
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY 4,105.9 4,249.7 3,974.4
Questar Gas [Member]      
Current Assets      
Cash and cash equivalents 0 19.8 1.4
Notes receivable from Questar 0 0 30.6
Accounts receivable, net 81.2 66.4 102.6
Unbilled gas accounts receivable 41.5 93.7 56.3
Accounts receivable from affiliates 56.3 45.2 31.3
Gas stored underground 9.5 40.3 6.2
Materials and supplies 17.3 19.2 13.2
Current regulatory assets 42.1 78.3 24.0
Prepaid expenses and other 2.4 3.5 2.4
Deferred income taxes - current 0 0 2.9
Total Current Assets 250.3 366.4 270.9
Property, Plant and Equipment 2,400.7 2,352.3 2,230.0
Accumulated depreciation, depletion and amortization (791.5) (780.3) (754.3)
Net Property, Plant and Equipment 1,609.2 1,572.0 1,475.7
Noncurrent regulatory assets 20.3 21.3 15.4
Other noncurrent assets 9.2 9.3 9.5
TOTAL ASSETS 1,889.0 1,969.0 1,771.5
Current Liabilities      
Checks outstanding in excess of cash balances 0.4 0 0
Notes payable to Questar 35.8 119.3 0
Accounts payable and accrued expenses 126.0 111.9 111.3
Accounts payable to affiliates 71.4 78.7 65.6
Dividends payable to Questar 0 9.0 0
Customer advances 9.5 29.4 7.2
Current regulatory liabilities 4.3 12.5 15.2
Deferred income taxes - current 3.9 6.3 0
Total Current Liabilities 251.3 367.1 199.3
Long-term debt and capital lease obligation, less current portion 534.5 534.5 534.5
Deferred income taxes 377.5 377.5 340.6
Noncurrent regulatory liabilities 63.3 60.9 54.8
Customer contributions in aid of construction 28.0 29.2 32.0
Other noncurrent liabilities 2.8 2.8 3.1
COMMON SHAREHOLDERS' EQUITY      
Common stock 23.0 23.0 23.0
Additional paid-in capital 265.7 265.4 264.2
Retained earnings 342.9 308.6 320.0
Total Common Shareholders' Equity 631.6 597.0 607.2
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY 1,889.0 1,969.0 1,771.5
Questar Pipeline [Member]      
Current Assets      
Cash and cash equivalents 6.1 7.4 4.9
Notes receivable from Questar 35.9 40.1 46.6
Accounts receivable, net 16.8 17.9 17.5
Accounts receivable from affiliates 44.3 39.2 33.8
Gas stored underground 2.9 3.4 0.7
Materials and supplies 7.1 6.9 7.5
Current regulatory assets 0.9 1.3 5.8
Prepaid expenses and other 3.6 4.3 2.8
Deferred income taxes - current 1.9 1.9 1.8
Total Current Assets 119.5 122.4 121.4
Property, Plant and Equipment 1,837.5 1,827.7 1,782.8
Accumulated depreciation, depletion and amortization (687.9) (673.9) (640.6)
Net Property, Plant and Equipment 1,149.6 1,153.8 1,142.2
Investment in unconsolidated affiliate 24.5 24.7 25.2
Noncurrent regulatory and other assets 10.4 10.8 11.3
TOTAL ASSETS 1,304.0 1,311.7 1,300.1
Current Liabilities      
Accounts payable and accrued expenses 33.9 21.7 38.7
Accounts payable to affiliates 3.4 5.8 3.4
Dividends payable to Questar 0 16.0 0
Current regulatory liabilities 0.9 0.9 2.0
Current portion of long-term debt and capital lease obligation 25.1 25.1 0
Total Current Liabilities 63.3 69.5 44.1
Long-term debt and capital lease obligation, less current portion 433.7 433.7 458.8
Deferred income taxes 241.3 241.4 228.6
Noncurrent regulatory and other liabilities 16.0 15.9 15.9
COMMON SHAREHOLDERS' EQUITY      
Common stock 6.6 6.6 6.6
Additional paid-in capital 351.9 351.4 350.1
Retained earnings 213.6 215.7 218.8
Accumulated other comprehensive (loss) (22.4) (22.5) (22.8)
Total Common Shareholders' Equity 549.7 551.2 552.7
TOTAL LIABILITIES AND COMMON SHAREHOLDERS' EQUITY $ 1,304.0 $ 1,311.7 $ 1,300.1