v2.4.0.6
Consolidated Balance Sheets (USD $)
In Millions, unless otherwise specified
Dec. 31, 2012
Dec. 31, 2011
Utility:    
Electric plant in service $ 9,070.7 $ 8,165.4
Gas plant in service 878.4 852.9
Other plant in service 506.2 510.1
Accumulated depreciation (accum. depr.) (3,513.0) (3,206.0)
Net plant 6,942.3 6,322.4
Construction work in progress:    
Columbia Energy Center Units 1 and 2 emission controls (WPL) 130.4 9.0
Ottumwa Generating Station Unit 1 emission controls (IPL) 73.7 7.7
George Neal Generating Station Units 3 and 4 emission controls (IPL) 66.9 8.3
Other 147.8 232.2
Other, less accum. depr. 21.2 34.9
Total utility 7,382.3 6,614.5
Non-regulated and other:    
Non-regulated Generation, less accum. depr. 258.6 270.6
Alliant Energy Corporate Services, Inc. and other, less accum. depr. 197.1 148.2
Total non-regulated and other 455.7 418.8
Total property, plant and equipment 7,838.0 7,033.3
Current assets:    
Cash and cash equivalents 21.2 11.4
Accounts receivable, less allowance for doubtul accounts:    
Customer 94.9 88.1
Unbilled utility revenues 81.4 75.1
Other 209.4 114.9
Income tax refunds receivable 18.2 39.1
Production fuel, at weighted average cost 103.1 101.9
Materials and supplies, at weighted average cost 63.1 58.5
Gas stored underground, at weighted average cost 37.7 57.7
Regulatory assets 83.5 103.6
Prepaid gross receipts tax 40.4 40.2
Deferred income tax assets 170.2 22.8
Assets held for sale 27.9 119.6
Prepayments and other 43.3 37.7
Total current assets 994.3 870.6
Investments:    
Investment in American Transmission Company LLC 257.0 238.8
Other 62.0 61.9
Total investments 319.0 300.7
Other assets:    
Regulatory assets 1,528.9 1,391.4
Deferred charges and other 105.3 91.9
Total other assets 1,634.2 1,483.3
Total assets 10,785.5 9,687.9
Capitalization:    
Common stock 1.1 1.1
Additional paid-in capital 1,511.2 1,510.8
Retained earnings 1,630.7 1,510.2
Accumulated other comprehensive loss (0.8) (0.8)
Shares in deferred compensation trust - 216,030 and 262,735 shares at a weighted average cost of $33.61 and $31.68 per share (7.3) (8.3)
Total common equity 3,134.9 3,013.0
Cumulative preferred stock of Interstate Power and Light Company 145.1 145.1
Noncontrolling interest 1.8 1.8
Total equity 3,281.8 3,159.9
Cumulative preferred stock of Wisconsin Power and Light Company 60.0 60.0
Long-term debt, net (excluding current portion) 3,136.6 2,703.1
Total capitalization 6,478.4 5,923.0
Current liabilities:    
Current maturities of long-term debt 1.5 1.4
Commercial paper 217.5 102.8
Accounts payable 339.3 267.8
Regulatory liabilities 189.7 164.7
Accrued taxes 48.0 46.9
Accrued interest 48.0 46.6
Derivative liabilities 31.1 55.9
Liabilities held for sale 31.4 62.1
Other 113.5 107.0
Total current liabilities 1,020.0 855.2
Other long-term liabilities and deferred credits:    
Deferred income tax liabilities 1,934.2 1,592.2
Regulatory liabilities 726.4 745.4
Pension and other benefit obligations 364.0 312.7
Other 262.5 259.4
Total long-term liabilities and deferred credits 3,287.1 2,909.7
Total capitalization and liabilities 10,785.5 9,687.9
IPL [Member]
    
Utility:    
Electric plant in service 4,815.2 4,684.0
Gas plant in service 441.4 428.2
Other plant in service 289.1 281.3
Accumulated depreciation (accum. depr.) (1,930.7) (1,833.8)
Net plant 3,615.0 3,559.7
Construction work in progress:    
Ottumwa Generating Station Unit 1 emission controls (IPL) 73.7 7.7
George Neal Generating Station Units 3 and 4 emission controls (IPL) 66.9 8.3
Other 82.8 80.6
Other, less accum. depr. 19.8 19.8
Non-regulated and other:    
Total property, plant and equipment 3,858.2 3,676.1
Current assets:    
Cash and cash equivalents 4.5 2.1
Accounts receivable, less allowance for doubtul accounts:    
Customer 95.0 75.2
Income tax refunds receivable 14.9 28.4
Production fuel, at weighted average cost 75.2 67.7
Materials and supplies, at weighted average cost 33.3 31.5
Gas stored underground, at weighted average cost 17.2 25.5
Regulatory assets 47.6 59.0
Deferred income tax assets 79.3 13.5
Prepayments and other 24.6 20.2
Total current assets 391.6 323.1
Investments:    
Total investments 17.6 16.8
Other assets:    
Regulatory assets 1,170.3 1,058.3
Deferred charges and other 19.3 19.2
Total other assets 1,189.6 1,077.5
Total assets 5,457.0 5,093.5
Capitalization:    
Common stock 33.4 33.4
Additional paid-in capital 1,037.8 927.7
Retained earnings 448.0 433.3
Total common equity 1,519.2 1,394.4
Cumulative preferred stock of Interstate Power and Light Company 145.1 145.1
Total equity 1,664.3 1,539.5
Long-term debt, net (excluding current portion) 1,359.5 1,309.0
Total capitalization 3,023.8 2,848.5
Current liabilities:    
Current maturities of long-term debt 0 0
Commercial paper 26.3 7.1
Accounts payable 163.2 118.2
Accounts payable to associated companies 29.3 36.7
Regulatory liabilities 130.1 137.1
Accrued taxes 46.8 43.8
Accrued interest 22.8 22.8
Derivative liabilities 14.1 24.5
Other 36.2 32.3
Total current liabilities 468.8 422.5
Other long-term liabilities and deferred credits:    
Deferred income tax liabilities 1,087.3 936.9
Regulatory liabilities 571.3 584.2
Pension and other benefit obligations 122.9 101.9
Other 182.9 199.5
Total long-term liabilities and deferred credits 1,964.4 1,822.5
Total capitalization and liabilities 5,457.0 5,093.5
WPL [Member]
    
Utility:    
Electric plant in service 4,255.5 3,481.4
Gas plant in service 437.0 424.7
Other plant in service 217.1 228.8
Accumulated depreciation (accum. depr.) (1,582.3) (1,372.2)
Net plant 3,327.3 2,762.7
Leased Sheboygan Falls Energy Facility, less accumulated amortization of $46.7 and $40.6 77.0 83.2
Construction work in progress:    
Columbia Energy Center Units 1 and 2 emission controls (WPL) 130.4 9.0
Other 65.0 151.6
Other, less accum. depr. 1.4 15.1
Non-regulated and other:    
Total property, plant and equipment 3,601.1 3,021.6
Current assets:    
Cash and cash equivalents 0.7 2.7
Accounts receivable, less allowance for doubtul accounts:    
Customer 83.3 76.2
Unbilled utility revenues 81.4 75.1
Other 48.5 38.2
Production fuel, at weighted average cost 27.9 34.2
Materials and supplies, at weighted average cost 28.5 25.7
Gas stored underground, at weighted average cost 20.5 32.2
Regulatory assets 35.9 44.6
Prepaid gross receipts tax 40.4 40.2
Deferred income tax assets 85.6 6.0
Prepayments and other 16.0 10.9
Total current assets 468.7 386.0
Investments:    
Investment in American Transmission Company LLC 257.0 238.8
Other 19.6 19.8
Total investments 276.6 258.6
Other assets:    
Regulatory assets 358.6 333.1
Deferred charges and other 57.6 44.7
Total other assets 416.2 377.8
Total assets 4,762.6 4,044.0
Capitalization:    
Common stock 66.2 66.2
Additional paid-in capital 959.2 869.0
Retained earnings 557.6 507.2
Total common equity 1,583.0 1,442.4
Cumulative preferred stock of Wisconsin Power and Light Company 60.0 60.0
Long-term debt, net (excluding current portion) 1,331.5 1,082.2
Total capitalization 2,974.5 2,584.6
Current liabilities:    
Current maturities of long-term debt 0 0
Commercial paper 86.6 25.7
Accounts payable 126.4 98.5
Accounts payable to associated companies 13.2 20.5
Regulatory liabilities 59.6 27.6
Accrued taxes 28.3 9.1
Accrued interest 22.2 21.6
Derivative liabilities 17.0 31.4
Other 32.2 23.2
Total current liabilities 385.5 257.6
Other long-term liabilities and deferred credits:    
Deferred income tax liabilities 844.1 672.5
Regulatory liabilities 155.1 161.2
Capital lease obligations - Sheboygan Falls Energy Facility 99.1 103.3
Pension and other benefit obligations 159.7 128.0
Other 144.6 136.8
Total long-term liabilities and deferred credits 1,402.6 1,201.8
Total capitalization and liabilities $ 4,762.6 $ 4,044.0