Revenue - Deferred Revenue (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Product Information [Line Items]
Total current deferred revenue	$ 2,397	$ 3,360
Non-current deferred revenue	2,678	3,764
Total deferred revenue	5,075	7,124
Platform subscriptions and services revenue
Product Information [Line Items]
Total current deferred revenue	2,317	3,278
Non-current deferred revenue	2,678	3,764
Application transaction revenue
Product Information [Line Items]
Total current deferred revenue	$ 80	$ 82