Stockholders' Equity - Summary of Stock-Based Compensation Recorded in Expense Categories in Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	$ 2,397	$ 2,464	$ 4,889	$ 5,266
Cost of Services and Fulfillment [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	1,401	1,232	2,835	2,825
Selling and Marketing [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	399	423	848	785
General and Administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	$ 597	$ 809	$ 1,206	$ 1,656