v3.20.4
Income Taxes - Provision for Income Tax Recovery/Expense (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Income Tax Disclosure [Abstract]    
Income (loss) before income taxes $ 240,364 $ (95,815)
Expected income tax (expense) recovery at Canadian statutory income tax rate of 26.5% (2019 - 26.5%) (63,711) 25,400
Permanent differences 138,601 (74,024)
Foreign tax rate differential 16,825 (1,770)
Tax credits earned during the year 1,900 1,571
Other items 4,503 1,468
Change in valuation allowance (18,973) 18,328
Recovery of (provision for) income taxes $ 79,145 $ (29,027)
Canada Revenue Agency    
Income Tax Disclosure [Abstract]    
Canadian statutory income tax rate 26.50% 26.50%
Operating Loss Carryforwards [Line Items]    
Canadian statutory income tax rate 26.50% 26.50%