Revenue from Contracts with Clients and Customers - Summary of Revenues Disaggregated (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Disaggregated revenue	$ 76,699	$ 72,149
North America
Disaggregation of Revenue [Line Items]
Disaggregated revenue	64,295	60,320
Europe
Disaggregation of Revenue [Line Items]
Disaggregated revenue	12,404	11,829
PFS Operations
Disaggregation of Revenue [Line Items]
Disaggregated revenue	54,920	53,430
PFS Operations | North America
Disaggregation of Revenue [Line Items]
Disaggregated revenue	45,098	43,602
PFS Operations | Europe
Disaggregation of Revenue [Line Items]
Disaggregated revenue	9,822	9,828
LiveArea Professional Services
Disaggregation of Revenue [Line Items]
Disaggregated revenue	21,779	18,719
LiveArea Professional Services | North America
Disaggregation of Revenue [Line Items]
Disaggregated revenue	19,197	16,718
LiveArea Professional Services | Europe
Disaggregation of Revenue [Line Items]
Disaggregated revenue	2,582	2,001
Service fee revenue
Disaggregation of Revenue [Line Items]
Disaggregated revenue	54,298	51,439
Service fee revenue | PFS Operations
Disaggregation of Revenue [Line Items]
Disaggregated revenue	33,431	33,055
Service fee revenue | LiveArea Professional Services
Disaggregation of Revenue [Line Items]
Disaggregated revenue	20,867	18,384
Product revenue, net
Disaggregation of Revenue [Line Items]
Disaggregated revenue	7,533	7,499
Product revenue, net | PFS Operations
Disaggregation of Revenue [Line Items]
Disaggregated revenue	7,533	7,499
Product revenue, net | LiveArea Professional Services
Disaggregation of Revenue [Line Items]
Disaggregated revenue	0	0
Pass-through revenue
Disaggregation of Revenue [Line Items]
Disaggregated revenue	14,868	13,211
Pass-through revenue | PFS Operations
Disaggregation of Revenue [Line Items]
Disaggregated revenue	13,956	12,876
Pass-through revenue | LiveArea Professional Services
Disaggregation of Revenue [Line Items]
Disaggregated revenue	912	335
Over time
Disaggregation of Revenue [Line Items]
Disaggregated revenue	69,166	64,650
Over time | PFS Operations
Disaggregation of Revenue [Line Items]
Disaggregated revenue	47,387	45,931
Over time | LiveArea Professional Services
Disaggregation of Revenue [Line Items]
Disaggregated revenue	21,779	18,719
Point-in-time
Disaggregation of Revenue [Line Items]
Disaggregated revenue	7,533	7,499
Point-in-time | PFS Operations
Disaggregation of Revenue [Line Items]
Disaggregated revenue	7,533	7,499
Point-in-time | LiveArea Professional Services
Disaggregation of Revenue [Line Items]
Disaggregated revenue	$ 0	$ 0