Summary of Significant Accounting Policies - Schedule of Settlement and Merchant Reserve Assets and Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Settlement And Merchant Reserve Assets And Liabilities [Abstract]
Settlement assets	$ 126,565	$ 149,785
Merchant reserve assets	16,119	16,246
Total	142,684	166,031	$ 152,706
Settlement liabilities	125,011	148,818
Merchant reserve liabilities	16,119	16,246
Total	$ 141,130	$ 165,064