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Financial Instruments - Additional Information (Details)
$ in Millions, $ in Millions
 12 Months Ended
Dec. 31, 2020
CAD ($)
day
Dec. 31, 2019
CAD ($)
day
Dec. 31, 2020
USD ($)
day
Dec. 31, 2020
AUD ($)
day
Disclosure of nature and extent of risks arising from financial instruments [line items]        
Maximum amount of credit risk exposure $ 1,649,600,000 $ 1,682,400,000    
Number of internal target days of revenue in trade receivables | day 58 61 58 58
Decrease through write-off, financial assets $ 2,000,000.0 $ 1,700,000    
Percentage of changes in equity prices 1.00%   1.00% 1.00%
Equity price risk        
Disclosure of nature and extent of risks arising from financial instruments [line items]        
Net income increase (decrease) $ 1,300,000      
Revolving credit facility        
Disclosure of nature and extent of risks arising from financial instruments [line items]        
Amount of revolving credit facility 800,000,000.0     $ 800.0
Unused capacity of the facility 786,500,000 282,600,000    
Forward contract        
Disclosure of nature and extent of risks arising from financial instruments [line items]        
Unrealized loss on forward contract 500,000      
Derivative notional amount $ 96,000,000.0   $ 75.0  
Cash flow hedges        
Disclosure of nature and extent of risks arising from financial instruments [line items]        
Interest rate swap agreement, amount 160,000,000.0      
Interest rate swap agreement, fixed Interest rate 2.295%   2.295% 2.295%
Unrealized gain (loss) on interest rate swap $ (5,400,000) (1,500,000)    
Gain (loss) on interest rate swap, net of tax $ (4,100,000) $ (1,100,000)