Revenue - Deferred Revenue (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Product Information [Line Items]
Total current deferred revenue	$ 2,010	$ 2,397
Non-current deferred revenue	1,779	2,678
Total deferred revenue	3,789	5,075
Platform subscriptions and services revenue
Product Information [Line Items]
Total current deferred revenue	1,927	2,317
Non-current deferred revenue	1,779	2,678
Application transaction revenue
Product Information [Line Items]
Total current deferred revenue	$ 83	$ 80