XML 24 R69.htm IDEA: XBRL DOCUMENT v3.19.3
Stock incentive plans - Plans (Details) - shares
Sep. 30, 2019
Dec. 31, 2018
Stock options    
Stock incentive plans    
Number of options outstanding 277,000 304,000
Stock options | 2011 Plan    
Stock incentive plans    
Number of options outstanding 269,000  
RSUs | 2011 Plan    
Stock incentive plans    
RSUs outstanding 800,000