Business Combinations - Additional Information (Details) - USD ($)
$ in Thousands
 3 Months Ended 4 Months Ended 12 Months Ended
Aug. 31, 2016
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2016
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Business Acquisition [Line Items]                          
Total revenues   $ 35,340 $ 32,196 $ 29,026 $ 26,561 $ 24,474 $ 21,661 $ 19,425 $ 18,047   $ 123,123 $ 83,607 $ 51,677
Net loss   $ 15,664 $ 6,619 $ 7,541 $ 9,335 $ 7,207 $ 6,735 $ 6,538 $ 4,254   $ 39,159 $ 24,734 $ 16,752
Runbook Company B.V.                          
Business Acquisition [Line Items]                          
Date of acquisition                     Aug. 31, 2016    
Total purchase consideration $ 34,052                        
Escrow amount 3,100                        
Escrow deposit maturity, description                     Upon the finalization of the working capital adjustment, the amount of the purchase price allocated to goodwill may change. A portion of the purchase price totaling $3.1 million, was paid into escrow for indemnification obligations relating to potential breach of representations and warranties of the sellers and any amounts remaining in escrow after satisfaction of any resolved claims, will be released from escrow on the one-year anniversary of the acquisition.    
Acquisition related costs $ 1,600                        
Weighted average lives of intangible assets 8 years 8 months 12 days                        
Total revenues                   $ 800      
Net loss                   $ 1,700