Segment and Geographical Information - Revenue by Geographic Area Based on Billing Address of Freelancers and Clients (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	$ 64,113	$ 52,262	$ 186,012	$ 147,793
Freelancers
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	41,379	33,865	119,951	96,973
Freelancers | United States
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	10,273	6,839	28,930	19,184
Freelancers | India
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	6,561	5,712	19,134	16,183
Freelancers | Philippines
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	4,377	3,795	12,535	10,839
Freelancers | Rest of world
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	20,168	17,519	59,352	50,767
Clients
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	22,734	18,397	66,061	50,820
Clients | United States
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	16,504	14,339	50,153	39,703
Clients | Rest of world
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	$ 6,230	$ 4,058	$ 15,908	$ 11,117