Income Taxes - Net Deferred Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Tangible and intangible depreciable assets	$ 6,978	$ 8,123
Stock compensation	12,321	6,515
Provisions	934	1,020
Other, net	35	0
Lease liability	137	0
Net operating loss carry forwards	116,345	74,721
Capital loss carryforward	178	178
Canada scientific research and experimental development expenditures	5,471	5,467
U.S. research and development tax credits	17,080	10,613
Total gross deferred tax assets	159,479	106,637
Less valuation allowance	(159,357)	(106,637)
Net deferred tax assets	122	0
Deferred tax liabilities:
Right-of-use Asset	(122)	0
Net deferred income taxes	$ 0	$ 0