Shareholders' Equity - Summary of Stock Options Granted (Detail) $ / shares in Units, $ / shares in Units, $ in Thousands, $ in Thousands					6 Months Ended
	Jun. 30, 2020 CAD ($) $ / shares shares	Jun. 30, 2020 CAD ($) $ / shares shares	Dec. 31, 2019 CAD ($) $ / shares shares	Dec. 31, 2019 CAD ($) $ / shares shares	Jun. 30, 2020 CAD ($) $ / shares shares	Jun. 30, 2020 CAD ($) $ / shares shares	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Canadian Dollar Under the New Option Stock Plan
Number of Options
Beginning balance (in shares)					2,356,413	2,356,413
Granted (in shares)					345,750	345,750
Exercised (in shares)					(106,982)	(106,982)
Forfeited (in shares)					(47,435)	(47,435)
Ending balance (in shares)	2,547,746	2,547,746	2,356,413	2,356,413	2,547,746	2,547,746
Weighted Average Exercise Price
Beginning balance (in dollars per share) | (per share)					$ 16.21	$ 12.46
Granted (in dollars per share) | (per share)					48.83	35.74
Exercised (in dollars per share) | (per share)					15.82	11.89
Forfeited (in dollars per share) | (per share)					27.35	20.21
Ending balance (in dollars per share) | (per share)	$ 20.45	$ 15.06	$ 16.21	$ 12.46	$ 20.45	$ 15.06
Weighted- Average Contractual Term (years)	6 years 7 months 20 days	6 years 7 months 20 days	6 years 8 months 12 days	6 years 8 months 12 days
Aggregate intrinsic value Outstanding	$ 73,898	$ 73,898	$ 101,404	$ 101,404	$ 73,898	$ 73,898	$ 53,995	$ 77,807
U.S Dollar Under the New Option Stock Plan
Number of Options
Beginning balance (in shares)					2,853,346	2,853,346
Granted (in shares)					1,036,150	1,036,150
Exercised (in shares)					(45,464)	(45,464)
Forfeited (in shares)					(96,958)	(96,958)
Ending balance (in shares)	3,747,074	3,747,074	2,853,346	2,853,346	3,747,074	3,747,074
Weighted Average Exercise Price
Beginning balance (in dollars per share) | $ / shares						$ 15.85
Granted (in dollars per share) | $ / shares						36.32
Exercised (in dollars per share) | $ / shares						11.61
Forfeited (in dollars per share) | $ / shares						15.84
Ending balance (in dollars per share) | $ / shares		$ 21.56		$ 15.85		$ 21.56
Weighted- Average Contractual Term (years)	8 years 7 months 6 days	8 years 7 months 6 days	8 years 7 months 28 days	8 years 7 months 28 days
Aggregate intrinsic value Outstanding | $							$ 55,528	$ 84,481