Income Taxes - Summary of Reconciliation of Amount of Income Taxes Compared to Expected Income Taxes Calculated at Combined Federal and Provincial Enacted Statutory Tax Rate (Details) - CAD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Net loss before income taxes	$ (1,509,054)	$ (707,913)	$ (51,456)
Expected tax rate	26.50%	26.50%	26.50%
Expected income tax recovery (expense)	$ 399,899	$ 187,597	$ 13,636
Non-deductible and non-taxable items	22,947	(34,999)	(6,297)
Non-deductible fair value changes on Acreage Arrangement	(170,975)
Non-taxable fair value changes on warrant derivative liability	210,715
Non-deductible share-based compensation	(84,873)	(72,463)	(13,013)
Change in valuation allowance	(215,975)	(78,425)	(3,234)
Effect of tax rates outside of Canada	(3,248)	(4,060)
Non-taxable portion of capital gains and losses	(34,961)		9,421
Other	(1,915)	(1,762)	(121)
Income tax recovery (expense)	$ 121,614	$ (4,112)	$ 392