Classification of Compensation Expense Associated with Share-Based Payments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Recognized Share Based Compensation Expense [Line Items]
Allocated Share-based Compensation Expense	$ 368	$ 583
Cost Of Revenue
Recognized Share Based Compensation Expense [Line Items]
Allocated Share-based Compensation Expense	80	58
Sales and Marketing
Recognized Share Based Compensation Expense [Line Items]
Allocated Share-based Compensation Expense	139	121
General and Administrative Expense
Recognized Share Based Compensation Expense [Line Items]
Allocated Share-based Compensation Expense	115	358
Engineering And Development
Recognized Share Based Compensation Expense [Line Items]
Allocated Share-based Compensation Expense	$ 34	$ 46