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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	$ 2,464	$ 2,848	$ 5,266	$ 5,533
Cost of Services and Fulfillment [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	1,232	1,567	2,825	3,030
Selling and Marketing [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	423	485	785	925
General and Administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	$ 809	$ 796	$ 1,656	$ 1,578