Accrued Liabilities - Components of Accrued Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Components of accrued liabilities
Accrued bonuses	$ 2,524	$ 2,245
Accrued vacation	2,275	1,838
Accrued payroll related liabilities	2,217	1,364
Accrued commissions	2,122	2,229
Income tax related accruals	709	498
Accrued software expense	673	1,668
Short-term portion of lease abandonment accrual	580	580
Deferred rent	559	526
Accrued sales and use tax	308	1,482
Other accrued expenses	2,402	1,850
Total	$ 14,369	$ 14,280