v3.19.3.a.u2
Equity method investments in unconsolidated affiliates (Details)
$ in Millions
1 Months Ended 12 Months Ended 41 Months Ended
Nov. 30, 2017
Dec. 31, 2019
USD ($)
item
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Dec. 31, 2017
USD ($)
Jun. 18, 2018
USD ($)
Jun. 17, 2018
Jun. 30, 2017
USD ($)
Asset acquisitions                
Percentage of equity method ownership interest           100.00%    
Carrying value   $ 96.6 $ 140.8          
Equity in earnings of unconsolidated affiliates   (3.0) 43.2 $ (54.8)        
Distributions from equity method investments   59.5 61.6 47.3        
Deficit in earnings of equity method investments, net of distributions   $ (62.5) (18.4) (102.1)        
Frederickson                
Asset acquisitions                
Percentage of equity method ownership interest   50.20%            
Carrying value   $ 65.2 72.0 108.3 $ 108.3      
Number of ownership parties | item   2            
Equity in earnings of unconsolidated affiliates   $ 9.1 6.9 (27.9)        
Orlando Cogen, LP                
Asset acquisitions                
Percentage of equity method ownership interest   50.00%            
Carrying value   $ 3.6 4.5          
Equity in earnings of unconsolidated affiliates   $ 33.0 30.1 25.6        
Koma Kulshan Associates                
Asset acquisitions                
Percentage of equity method ownership interest           50.00% 49.75%  
Carrying value           $ 1.1    
Equity in earnings of unconsolidated affiliates     0.6 0.7        
Chambers Cogen, LP                
Asset acquisitions                
Percentage of equity method ownership interest   40.00%            
Carrying value   $ 9.0 64.3         $ 124.0
Equity in earnings of unconsolidated affiliates   $ (46.0) $ 5.6 (42.6)        
Chambers Cogen, LP | Earnings from unconsolidated affiliates                
Asset acquisitions                
Percentage of equity method ownership interest   40.00%            
Carrying value   $ 58.2            
Selkirk Cogen Partners, LP                
Asset acquisitions                
Equity in earnings of unconsolidated affiliates       (10.6)        
Distributions from equity method investments         0.0      
Deficit in earnings of equity method investments, net of distributions         $ (2.6)      
Selkirk Cogen Partners, LP | Earnings from unconsolidated affiliates                
Asset acquisitions                
Gain on sale of equity method investment       $ 1.0        
Selkirk Cogen Partners, LP | Disposal Group, Disposed of by Sale, Not Discontinued Operations                
Asset acquisitions                
Sale of ownership percentage 17.70%              
Craven County Wood Energy, LP                
Asset acquisitions                
Percentage of equity method ownership interest   50.00%            
Carrying value   $ 9.5            
Equity in earnings of unconsolidated affiliates   $ 0.1            
Grayling Generating Station, LP                
Asset acquisitions                
Percentage of equity method ownership interest   30.00%            
Carrying value   $ 9.3            
Equity in earnings of unconsolidated affiliates   $ 0.8