Accrued Liabilities - Components of Accrued Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Components of accrued liabilities
Accrued vacation	$ 2,449	$ 1,838
Accrued bonuses	2,324	2,245
Accrued commissions	1,583	2,229
Accrued payroll related liabilities	1,171	1,364
Income tax related accruals	639	498
Short-term portion of lease abandonment accrual	580	580
Deferred rent	548	526
Accrued software expense	279	1,668
Accrued sales and use tax	713	1,482
Other accrued expenses	2,531	1,850
Total	$ 12,817	$ 14,280