Stockholders' Equity - Summary of Stock-Based Compensation Recorded in Expense Categories (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	$ 1,860	$ 1,409	$ 4,588	$ 3,921
Cost of Services and Fulfillment [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	1,061	835	2,708	2,213
Selling and Marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	321	207	893	638
General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	$ 478	$ 367	$ 987	$ 1,070