Stockholders’ Equity and Equity-Based Compensation - Summary of non-cash equity-based compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Non-cash equity-based compensation expense related to the 2012 Plan and 2012 ESPP
Non-cash equity-based compensation	$ 5,509	$ 5,959	$ 17,884	$ 17,994
Stock options
Non-cash equity-based compensation expense related to the 2012 Plan and 2012 ESPP
Non-cash equity-based compensation	1,327	1,521	4,394	4,487
RSUs
Non-cash equity-based compensation expense related to the 2012 Plan and 2012 ESPP
Non-cash equity-based compensation	4,182	4,438	13,490	13,507
Cost of revenue
Non-cash equity-based compensation expense related to the 2012 Plan and 2012 ESPP
Non-cash equity-based compensation	55	116	245	430
Sales and marketing
Non-cash equity-based compensation expense related to the 2012 Plan and 2012 ESPP
Non-cash equity-based compensation	366	404	1,623	1,546
Product development
Non-cash equity-based compensation expense related to the 2012 Plan and 2012 ESPP
Non-cash equity-based compensation	1,395	1,295	3,822	4,510
General and administrative
Non-cash equity-based compensation expense related to the 2012 Plan and 2012 ESPP
Non-cash equity-based compensation	$ 3,693	$ 4,144	$ 12,194	$ 11,508