Summary of Significant Accounting Policies - Summary of Stock-Based Compensation Expense Recorded in Expense Categories (Detail) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] | |||
| Total allocated share-based compensation expense | $ 7,976 | $ 8,347 | $ 7,444 |
| Cost of Services and Fulfillment [Member] | |||
| Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] | |||
| Total allocated share-based compensation expense | 4,431 | 4,573 | 4,316 |
| Selling and Marketing [Member] | |||
| Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] | |||
| Total allocated share-based compensation expense | 1,054 | 1,152 | 1,132 |
| General and Administrative [Member] | |||
| Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] | |||
| Total allocated share-based compensation expense | $ 2,491 | $ 2,622 | $ 1,996 |