Annual report pursuant to Section 13 and 15(d)

Geographical Information (Details)

v3.8.0.1
Geographical Information (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Revenues $ 182,862 $ 175,614 $ 167,417 $ 157,786 $ 155,480 $ 149,155 $ 141,708 $ 131,821 $ 683,679 $ 578,164 $ 420,919
Property, Plant and Equipment, Net 35,909       33,000       35,909 33,000  
United States                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Revenues                 617,835 519,998 388,098
Property, Plant and Equipment, Net 30,647       28,713       30,647 28,713  
International                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Revenues                 65,844 58,166 $ 32,821
India                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Property, Plant and Equipment, Net 4,907       3,596       4,907 3,596  
Other                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Property, Plant and Equipment, Net $ 355       $ 691       $ 355 $ 691