Summary of Significant Accounting Policies - Summary of Stock-Based Compensation Expense Recorded in Expense Categories (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	$ 8,347	$ 7,444	$ 6,051
Cost of Services and Fulfillment [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	4,573	4,316	3,585
Selling and Marketing [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	1,152	1,132	1,136
General and Administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	$ 2,622	$ 1,996	$ 1,330