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Long-term debt - Narrative (Detail)
Jun. 01, 2020
USD ($)
Apr. 30, 2020
USD ($)
Jun. 30, 2020
USD ($)
credit_facility
Feb. 24, 2020
USD ($)
Feb. 14, 2020
CAD ($)
Debt Instrument [Line Items]          
Short-term debt     $ 659,558,000    
Senior Unsecured Notes          
Debt Instrument [Line Items]          
Debt repaid upon maturity   $ 100,000,000      
Senior Unsecured Notes | Algonquin Power Senior Unsecured Revolving Facility Maturing June 2021 [Member] | Letter of Credit          
Debt Instrument [Line Items]          
Line of credit facility, maximum borrowing capacity       $ 350,000,000  
Senior Unsecured Notes | Senior Unsecured Bank Credit Facilities | Line of Credit          
Debt Instrument [Line Items]          
Line of credit facility, maximum borrowing capacity     $ 1,600,000,000    
Number of New Credit Facilities | credit_facility     3    
Line of credit facility, amount outstanding     $ 400,000,000    
Senior Unsecured Notes | Senior Unsecured Debentures Due February 2050          
Debt Instrument [Line Items]          
Par value         $ 200,000,000
Weighted average coupon         3.315%
Senior Secured Utility Bonds          
Debt Instrument [Line Items]          
Debt repaid upon maturity $ 100,000,000