Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Summary of ESPP Activity (Details)

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Stockholders' Equity - Summary of ESPP Activity (Details) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Mar. 02, 2015
Sep. 01, 2014
Mar. 03, 2014
Dec. 31, 2015
Dec. 31, 2014
Sep. 01, 2015
Class Of Stock [Line Items]            
Payroll deductions used to purchase shares       $ 701 $ 413  
ESPP            
Class Of Stock [Line Items]            
Employee accumulated payroll deductions $ 361 $ 343 $ 414     $ 388
Total shares purchased 12,555 18,551 30,358      
Payroll deductions used to purchase shares $ 359 $ 342 $ 413      
Transfer to next offering period $ 3 $ 1 $ 1      
FMV at enrollment date per share $ 33.62 $ 21.69 $ 16.00     $ 49.25
FMV at purchase date per share 49.25 33.62 21.69      
Purchase price per share $ 28.58 $ 18.44 $ 13.60