v3.3.1.900
Discontinued operations (Details) - USD ($)
$ / shares in Units, $ in Millions
1 Months Ended 3 Months Ended 12 Months Ended
Jun. 26, 2015
Nov. 05, 2013
Mar. 31, 2014
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Mar. 06, 2014
Discontinued operations and other divestitures                              
Gain on the disposal                           $ (32.8)  
Current assets:                              
Total current assets               $ 790.4         $ 790.4    
Long-term liabilities                              
Liabilities held for sale               271.8         271.8    
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]                              
(Loss) income from discontinued operations, net of tax       $ (1.3) $ (0.5) $ 33.6 $ (12.3) (7.3) $ (7.7) $ (5.7) $ (8.3) $ 19.5 (29.0) (0.2)  
(Loss) income from operations of discontinued businesses, net of noncontrolling interests                       $ 30.5 $ (12.6) $ 3.2  
Net Cash Provided by (Used in) Discontinued Operations [Abstract]                              
Basic and diluted earnings (loss) per share related to income (loss) from discontinued operations (in dollars per share)                       $ 0.25 $ (0.10) $ 0.02  
Discontinued Operations, Disposed of by Sale                              
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]                              
Revenue                       $ 34.8 $ 79.3 $ 149.9  
Fuel                           30.6  
Operations and maintenance                       10.8 21.1 33.2  
Depreciation and amortization                       10.3 40.3 52.1  
Total Project expenses                       21.1 61.4 115.9  
Change in fair value of derivatives                       (0.7) (15.5) 34.7  
Equity in earnings of unconsolidated affiliates                       (0.5) 0.3 1.1  
Interest expense, net                       (6.7) (14.2) (18.1)  
Gain (loss) on sale of asset                       46.8 2.0 (37.8)  
Total Project other income (expense)                       38.9 (27.4) (20.1)  
(Loss) income from discontinued businesses                       52.6 (9.5) 13.9  
Income tax expense                       33.1 19.5 14.1  
(Loss) income from discontinued operations, net of tax                       19.5 (29.0) (0.2)  
Net loss attributable to noncontrolling interests of discontinued businesses                       (11.0) (16.4) (3.4)  
(Loss) income from operations of discontinued businesses, net of noncontrolling interests                       30.5 (12.6) $ 3.2  
Cadillac and Piedmont Projects                              
Discontinued operations and other divestitures                              
Value of asset management contracts assigned   $ 0.5                          
Piedmont                              
Discontinued operations and other divestitures                              
Percentage acquired in entity   2.00%                          
Final ownership interest (as a percent)   100.00%                          
Wind Projects | Discontinued Operations, Disposed of by Sale                              
Discontinued operations and other divestitures                              
Gain on the disposal $ 46.8                            
Wind Projects | Discontinued Operations, Held-for-sale                              
Current assets:                              
Cash and cash equivalents               3.9         3.9    
Accounts receivable               11.2         11.2    
Other current assets               2.4         2.4    
Total current assets               17.5         17.5    
Non-current assets:                              
Plant, property & equipment               710.5         710.5    
Equity investments in unconsolidated affiliates               37.0         37.0    
Other intangible assets, net               4.3         4.3    
Restricted cash               19.1         19.1    
Other assets               2.0         2.0    
Assets held for sale               790.4         790.4    
Current liabilities:                              
Accounts payable and other accrued liabilities               5.9         5.9    
Current portion of long-term debt               6.4         6.4    
Current portion of derivative instruments liability               3.1         3.1    
Total current liabilities               15.4         15.4    
Long-term liabilities                              
Long-term debt               242.4         242.4    
Derivative instruments liability               10.0         10.0    
Other long-term liabilities               4.0         4.0    
Liabilities held for sale               271.8         271.8    
Noncontrolling interests held for sale               $ 239.0         239.0    
Wind Projects | APT | Discontinued Operations, Disposed of by Sale                              
Discontinued operations and other divestitures                              
Consideration received on disposal interests $ 335.0                            
Ownership interest sold (as a percent) 100.00%                            
Proceeds from disposal $ 335.0                            
Net Cash Provided by (Used in) Discontinued Operations [Abstract]                              
Cash provided by operating activities                       21.9 48.3    
Cash (used in) provided by investing activities                       $ (12.8) $ 4.8    
Rollcast Energy, Inc. | Discontinued Operations, Disposed of by Sale                              
Discontinued operations and other divestitures                              
Ownership interest sold (as a percent)   60.00%                          
Amount paid to minority owner   $ 0.5                          
Outstanding debt forgiven   $ 1.0                          
Greeley                              
Discontinued operations and other divestitures                              
Consideration received on disposal interests                             $ 1.0
Gain on the disposal     $ 2.1                        
Greeley | Discontinued Operations, Disposed of by Sale                              
Discontinued operations and other divestitures                              
Consideration received on disposal interests     $ 1.0               $ 1.0