v3.8.0.1
Debt - Additional Information (Detail) - USD ($)
1 Months Ended 12 Months Ended
Feb. 29, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Debt Instrument [Line Items]        
Debt instrument term   If the outstanding principal during any month is at least $15.0 million, the Company must also maintain a minimum net income threshold based on non-GAAP operating measures.    
Debt amount outstanding   $ 0    
Repayment of equipment financing   307,000 $ 271,000 $ 1,704,000
December Equipment Financing Agreement [Member]        
Debt Instrument [Line Items]        
Debt amount outstanding   $ 26,000    
Debt issuance date   Dec. 31, 2015    
Computer equipment and support purchased   $ 604,000    
Repayment of equipment financing $ 604,000      
Repayment period of obligation under the agreement   2 years    
Secured Line of Credit [Member]        
Debt Instrument [Line Items]        
Line of credit, agreement start date   Nov. 19, 2015    
Line of credit maximum borrowing capacity   $ 20,000,000    
Percentage points added to prime rate or LIBOR   2.50%    
Minimum [Member]        
Debt Instrument [Line Items]        
Minimum outstanding principal threshold limit   $ 15,000,000