Share Based Payments - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands, $ in Millions	9 Months Ended		12 Months Ended
	Dec. 31, 2016 USD ($) shares	Dec. 31, 2016 CAD ($) $ / shares shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2017 CAD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Stock Options, Beginning balance outstanding | shares	1,335,072	1,335,072	1,969,000	1,969,000
Number of Stock Options, Granted | shares	707,000	707,000	868,902	868,902
Number of Stock Options, Forfeited | shares	(6,250)	(6,250)	(153,067)	(153,067)
Number of Stock Options, Cancelled | shares	(24,822)	(24,822)	(62,689)	(62,689)
Number of Stock Options, Exercised | shares	(42,000)	(42,000)	(173,500)	(173,500)
Number of Stock Options, Ending balance outstanding | shares	1,969,000	1,969,000	2,448,646	2,448,646
Number of Stock Options, Exercisable | shares				1,451,739
Weighted Average Exercise Price, Beginning balance outstanding | $ / shares		$ 5.40		$ 6.00
Weighted Average Exercise Price, Granted | $ / shares		6.90		11.15
Weighted Average Exercise Price, Forfeited | $ / shares		3.00		11.45
Weighted Average Exercise Price, Cancelled | $ / shares		3.00		13.75
Weighted Average Exercise Price, Exercised | $ / shares		3.00		5.15
Weighted Average Exercise Price, Ending balance outstanding | $ / shares		$ 6.00		7.35
Weighted Average Exercise Price, Exercisable | $ / shares				$ 5.70
Aggregate Intrinsic Value, Beginning balance outstanding | $		$ 1,581		$ 8,218
Aggregate Intrinsic Value, Exercised | $	$ 0.1		$ 1.3
Aggregate Intrinsic Value, Ending balance outstanding | $		$ 8,218		21,089
Aggregate Intrinsic Value, Exercisable | $				$ 14,892