Segment and Related Information - Identifiable Assets by Geographic Area (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	$ 343,749	$ 189,612	$ 94,681
United States
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	322,065	178,226	84,652
International
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	$ 21,684	$ 11,386	$ 10,029