Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income taxes
Pre-change net operating losses that can be used in future years	$ 13,500
Net operating losses not subject to IRC section 382	450,900
Deferred tax assets, U.S. net operating loss carryforwards	464,400
Amount of net operating loss carryforwards that will expire due to IRC Section 382 limitations	4,400
Net operating loss carryforwards	120,992	$ 64,014
Un-repatriated foreign earnings	0
Restated adjustment
Income taxes
Net operating loss carryforwards	205,200	25,000	$ 43,400
Canada
Income taxes
Research and experimental development expenditure carryforwards	17,200
Canadian ITC credit carryforwards	1,300
Foreign
Income taxes
Net operating loss carryforwards	10,014	$ 9,576
Foreign | French
Income taxes
Unused net operating loss carryforwards	21,300
Foreign | Canada
Income taxes
Net operating loss carryforwards	$ 14,000