v3.6.0.2
Stockholders' equity (Details) - shares
shares in Thousands
Dec. 31, 2016
Dec. 31, 2015
Stockholders' equity    
Common stock authorized (in shares) 100,000 100,000
Shares of Common Stock reserved    
Total (in shares) 9,485 9,249
2001 Plan    
Shares of Common Stock reserved    
Outstanding stock options (in shares) 1,090 1,220
2011 Plan    
Shares of Common Stock reserved    
Outstanding stock options (in shares) 1,994 2,528
Outstanding RSUs (in shares) 3,825 1,819
Number of shares available for grant (in shares) 2,576 3,682