Goodwill and Intangible Assets - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill	$ 28,706	$ 24,879
Impairment of goodwill	0	0	0
Amortization expense	2,290	2,332	3,349
Amortization expense included in cost of subscription revenues	631	383	514
Selling and Marketing Expense
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization expense	$ 1,659	$ 1,949	$ 2,835