v3.5.0.2
Stock incentive plans - Options (Details) - Stock options
9 Months Ended
Sep. 30, 2016
Stock incentive plans  
Vesting period 4 years
Vesting percentage when the individual completes 12 months of continuous service 25.00%
Continuous service period of individual 12 months
Vesting percentage on a monthly basis 75.00%