Segment Information - Components of Services Revenue (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue from External Customer [Line Items]
Total net services revenue	$ 89,711	$ 65,606	$ 44,745
Maintenance and Support [Member]
Revenue from External Customer [Line Items]
Total net services revenue	54,795	44,353	33,647
Professional Services and Training [Member]
Revenue from External Customer [Line Items]
Total net services revenue	11,414	9,890	6,428
Subscriptions [Member]
Revenue from External Customer [Line Items]
Total net services revenue	$ 23,502	$ 11,363	$ 4,670