XML 78 R58.htm IDEA: XBRL DOCUMENT v3.23.1
Significant accounting policies - Additional Information (Detail)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2022
USD ($)
facility
Dec. 31, 2022
USD ($)
facility
Dec. 31, 2021
USD ($)
Significant Accounting Policies [Line Items]      
Number of electric generating facilities | facility 3 3  
Cost of plant in service $ 559,630 $ 559,630 $ 557,954
Liquidity available under the facilities 2,515,600 2,515,600 2,050,200
Accumulated depreciation related to commonly owned facilities 75,820 75,820 59,857
Expenditures   110,268 143,255
U.S. Tax reform   $ 159,568  
Number of power generating facilities | facility   2  
Generating assets of Long Sault 17,627,613 $ 17,627,613 16,797,503
Non-regulated energy sales   2,765,155 2,274,142
Interest expense on long-term debt and others   278,574 209,554
Asset impairment charges   (235,478) 0
Non-Regulated Energy      
Significant Accounting Policies [Line Items]      
Non-regulated energy sales   350,939 256,633
Long Sault and Saint-Damase Wind Powered Generating Facility | Primary Beneficiary | Power plant      
Significant Accounting Policies [Line Items]      
Generating assets of Long Sault 57,241 57,241 59,877
Long-term debt of Long Sault 15,024 15,024 18,344
Operating expenses and amortization   5,834 5,410
Interest expense on long-term debt and others   1,723 2,055
Long Sault and Saint-Damase Wind Powered Generating Facility | Primary Beneficiary | Power plant | Non-Regulated Energy      
Significant Accounting Policies [Line Items]      
Non-regulated energy sales   $ 19,752 $ 16,772
Renewable Energy Group      
Significant Accounting Policies [Line Items]      
Asset impairment charges $ (75,910)    
Minimum      
Significant Accounting Policies [Line Items]      
Ownership interest in commonly owned facilities   7.52%  
U.S. Tax reform   $ 100,374  
Lease renewal term 1 year 1 year  
Minimum | Renewable Energy Group      
Significant Accounting Policies [Line Items]      
Asset impairment charges $ 206,816    
Maximum      
Significant Accounting Policies [Line Items]      
Ownership interest in commonly owned facilities   60.00%  
U.S. Tax reform   $ 259,942  
Lease renewal term 5 years 5 years  
Maximum | Renewable Energy Group      
Significant Accounting Policies [Line Items]      
Asset impairment charges $ 282,726    
Power sales contracts | Minimum      
Significant Accounting Policies [Line Items]      
Intangible asset, useful life   6 years  
Power sales contracts | Maximum      
Significant Accounting Policies [Line Items]      
Intangible asset, useful life   25 years  
Interconnection agreements      
Significant Accounting Policies [Line Items]      
Intangible asset, useful life   40 years  
Customer relationships | Minimum      
Significant Accounting Policies [Line Items]      
Intangible asset, useful life   25 years  
Customer relationships | Maximum      
Significant Accounting Policies [Line Items]      
Intangible asset, useful life   40 years