Income Taxes - Summary of Income Tax Provision (Recovery) (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax [Line Items]
Current	$ 3,672	$ (11)	$ 430
Deferred	(6,462)	(5,855)	(2,730)
Provision For (Recovery Of) Income Taxes	(2,790)	(5,866)	(2,300)
US State [Member]
Income Tax [Line Items]
Current	260	8	8
Deferred	(434)	(751)	(187)
Provision For (Recovery Of) Income Taxes	(174)	(743)	(179)
Canadian [Member]
Income Tax [Line Items]
Current	3,412	(19)	422
Deferred	(1,149)	818	(757)
Provision For (Recovery Of) Income Taxes	2,263	799	(335)
US Federal [Member]
Income Tax [Line Items]
Deferred	(4,879)	(5,922)	(1,786)
Provision For (Recovery Of) Income Taxes	$ (4,879)	$ (5,922)	$ (1,786)

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration