Income Taxes - Unrecognized Tax Benefits (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2016
Dec. 31, 2017
Reconciliation of the beginning and ending amount of unrecognized tax benefits      
Unrecognized tax benefits balance at beginning of year   $ 437  
Reductions for tax positions of prior years   (469)  
Increases for currency translations   $ 32  
Pre-change net operating losses that can be used in future years $ 13,500    
Net operating losses not subject to IRC section 382 195,000    
Deferred tax assets, U.S. net operating loss carryforwards 208,000    
Unused net operating loss carryforwards $ 42,000    
Unrecognized loss recognition period 5 years    
Unrecognized loss from change in ownership that should be recognized during the recognition period $ 900    
Gross deferred tax liability 0   $ 209
Amount of net operating loss carryforwards that will expire due to IRC Section 382 limitations 1,900    
Net operating loss carryforwards 58,364   48,078
Un-repatriated foreign earnings 0    
Canada      
Reconciliation of the beginning and ending amount of unrecognized tax benefits      
Research and experimental development expenditure carryforwards 16,500    
Canadian ITC credit carryforwards     1,200
U.S.      
Reconciliation of the beginning and ending amount of unrecognized tax benefits      
Gross deferred tax liability     209
Net operating loss carryforwards 49,058   39,437
Foreign      
Reconciliation of the beginning and ending amount of unrecognized tax benefits      
Net operating loss carryforwards 9,306   $ 8,641
Foreign | French      
Reconciliation of the beginning and ending amount of unrecognized tax benefits      
Unused net operating loss carryforwards 17,600    
Foreign | Canada      
Reconciliation of the beginning and ending amount of unrecognized tax benefits      
Net operating loss carryforwards $ 13,600