Income taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of Income tax Recovery

Income tax recovery varies from the amounts that would be computed by applying the expected U.S. federal income tax rate (21%) as shown in the following table: 

	YEARS ENDED DECEMBER 31,
	2019			2018			2017
Statutory federal income tax rate		(21.0	)%		(21.0	)%		(35.0	)%
Change in tax rate		0.0			(0.1	)		(3.6	)
State income taxes		0.0			(1.4	)		(0.6	)
Foreign rate differential		(0.2	)		(4.3	)		7.9
Acquired in-process research and development		14.4			0.0			0.0
Stock compensation		2.6			2.8			2.0
Change in valuation allowance		(0.6	)		24.8			25.4
Expiration of NOLs (section 382)		5.4			—			—
Effect of the U.S. Tax Cuts and Jobs Act		—			—			4.6
Other		(0.6	)		(0.8	)		(0.7	)
Income tax recovery		—			—			—

Schedule of Net (Loss) Income Before Taxes

(in thousands)	YEARS ENDED DECEMBER 31,
Net loss before taxes:	2019			2018			2017
Canada	$	(2,129	)	$	(22,477	)	$	(43,758	)
U.S.		(67,313	)		(9,108	)		(6,425	)
Total	$	(69,442	)	$	(31,585	)	$	(50,183	)

Components of Deferred Income Tax Assets

Deferred income tax assets and liabilities result from the temporary differences between the amount of assets and liabilities recognized for financial statement and income tax purposes. The significant components of the deferred income tax assets are as follows:

(in thousands)	DECEMBER 31, 2019			DECEMBER 31, 2018
Canadian net operating losses	$	39,574		$	40,252
U.S. net operating losses		5,347			5,588
Research and development deductions and credits		11,062			9,588
Other		1,831			1,797
Less: valuation allowance		(57,814	)		(57,225	)
Net deferred income tax assets	$	—		$	—