Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Summary Of Significant Accounting Policies [Line Items]
Cash equivalents maturity period maximum	3 months
Cash equivalents	$ 200,000	$ 1,600,000
Accounts receivable number of days past due evaluated for doubtful accounts	90 days
Capitalized costs, amortization	$ 5,100,000
Impairment charge related to capitalized software development costs	0	0	$ 0
Impairment charges of long-lived asset	0	0	0
Goodwill impairment	$ 0	$ 0	$ 0
Percentage of deferred professional services revenues	6.00%	4.00%
Percentage of total revenues	10.00%	10.00%	10.00%
Percentage of total accounts receivable	10.00%	10.00%
Computer equipment, hardware and software [Member]
Summary Of Significant Accounting Policies [Line Items]
Property plant and equipment useful life	3 years
Furniture and fixtures [Member]
Summary Of Significant Accounting Policies [Line Items]
Property plant and equipment useful life	7 years
Leasehold improvements [Member]
Summary Of Significant Accounting Policies [Line Items]
Property plant and equipment useful life	5 years
Sales and marketing [Member]
Summary Of Significant Accounting Policies [Line Items]
Commissions expense	$ 11,800,000	$ 13,700,000	$ 15,700,000
Advertising costs	$ 5,600,000	$ 7,700,000	$ 5,300,000
U.S. [Member]
Summary Of Significant Accounting Policies [Line Items]
Products warranty period	180 days
Europe [Member]
Summary Of Significant Accounting Policies [Line Items]
Products warranty period	365 days
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Payment due days	30 days
Subscriptions term to customers	12 months
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Payment due days	60 days
Subscriptions term to customers	36 months