v2.4.0.8
Segment Information (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Sep. 30, 2013
Sep. 30, 2012
Financial information of reportable operating segments        
Operating Revenues $ 1,053.2 [1] $ 1,039.3 [1] $ 3,340.7 [1] $ 3,175.2 [1]
Other operation and maintenance 268.1 244.6 821.6 798.8
Depreciation and Amortization 96.9 91.8 289.1 269.7
Operating Income (Loss) 258.0 280.6 808.5 798.9
Equity in Earnings of Unconsolidated Affiliates 17.1 17.1 51.0 48.8
Interest Expense, net 62.0 60.9 190.3 181.3
Income Tax Expense (Benefit) 80.7 89.7 251.4 252.6
Net Income (Loss) 137.5 156.1 433.1 447.5
Capital Expenditures 190.4 163.5 497.7 477.5
Reportable Operating Segments Energy Utility [Member]
        
Financial information of reportable operating segments        
Operating Revenues 1,037.2 [1] 1,023.3 [1] 3,296.7 [1] 3,132.2 [1]
Other operation and maintenance 359.5 334.1 1,097.7 1,069.0
Depreciation and Amortization 79.9 74.7 238.2 218.8
Operating Income (Loss) 166.6 191.0 536.1 533.2
Equity in Earnings of Unconsolidated Affiliates 17.1 17.1 51.0 48.9
Interest Expense, net 33.0 31.4 103.1 92.6
Income Tax Expense (Benefit) 56.1 65.6 179.9 182.6
Net Income (Loss) 99.3 119.8 317.9 338.7
Capital Expenditures 178.1 161.2 476.2 468.2
Reportable Operating Segments Energy Non Utility [Member]
        
Financial information of reportable operating segments        
Operating Revenues 114.2 [1] 112.6 [1] 337.3 [1] 332.2 [1]
Other operation and maintenance 4.2 4.3 10.6 11.7
Depreciation and Amortization 16.8 16.8 50.3 50.3
Operating Income (Loss) 93.2 91.5 276.4 270.2
Equity in Earnings of Unconsolidated Affiliates 0 0 0 0
Interest Expense, net 16.4 16.6 49.4 50.1
Income Tax Expense (Benefit) 29.5 29.2 90.1 87.2
Net Income (Loss) 47.4 45.8 137.2 133.2
Capital Expenditures 10.4 1.8 17.5 5.6
Corporate and Other [Member]
        
Financial information of reportable operating segments        
Operating Revenues 0.4 [1],[2] 0.3 [1],[2] 1.0 [1],[2] 0.9 [1],[2]
Other operation and maintenance 1.9 [2] 2.0 [2] 4.1 [2] 4.7 [2]
Depreciation and Amortization 0.2 [2] 0.3 [2] 0.6 [2] 0.6 [2]
Operating Income (Loss) (1.8) [2] (1.9) [2] (4.0) [2] (4.5) [2]
Equity in Earnings of Unconsolidated Affiliates 0 [2] 0 [2] 0 [2] (0.1) [2]
Interest Expense, net 12.8 [2] 12.9 [2] 38.2 [2] 38.9 [2]
Income Tax Expense (Benefit) (4.9) [2] (5.1) [2] (18.6) [2] (17.2) [2]
Net Income (Loss) 137.4 [2] 156.1 [2] 432.9 [2] 448.0 [2]
Capital Expenditures 1.9 [2] 0.5 [2] 4.0 [2] 3.7 [2]
Eliminations and Reconciling Items [Member]
        
Financial information of reportable operating segments        
Operating Revenues (98.6) [1] (96.9) [1] (294.3) [1] (290.1) [1]
Other operation and maintenance (97.5) (95.8) (290.8) (286.6)
Depreciation and Amortization 0 0 0 0
Operating Income (Loss) 0 0 0 0
Equity in Earnings of Unconsolidated Affiliates 0 0 0 0
Interest Expense, net (0.2) 0 (0.4) (0.3)
Income Tax Expense (Benefit) 0 0 0 0
Net Income (Loss) (146.6) (165.6) (454.9) (472.4)
Capital Expenditures $ 0 $ 0 $ 0 $ 0
[1] An elimination for intersegment revenues is included in Operating Revenues. This elimination is primarily between We Power and Wisconsin Electric.
[2] Corporate & Other includes all other non-utility activities, primarily non-utility real estate investment and development by Wispark LLC, as well as interest on corporate debt.