Accrued Expenses and Other Current Liabilities - Severance Costs (Details) - Reductions in force - USD ($)
$ in Thousands
9 Months Ended
Sep. 30, 2016
Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]    
Severance costs $ 1,700  
Accrued expense   $ 485
Sales and Marketing    
Restructuring Cost and Reserve [Line Items]    
Severance costs 700  
Product Development    
Restructuring Cost and Reserve [Line Items]    
Severance costs 600  
Service Costs    
Restructuring Cost and Reserve [Line Items]    
Severance costs 300  
General and Administrative    
Restructuring Cost and Reserve [Line Items]    
Severance costs $ 100