Revenue - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Revenue [Line Items]
Software licensing arrangements warranty, description	The Company's software license arrangements typically provide the customer with a standard 90-day assurance-type warranty.
Software licensing arrangements warranty period	90 days
Initial post contract customer support period	1 year
Percentage of receivables as of March 31, 2018 or December 31, 2017	No customer accounted for more than 10% of the Company's consolidated receivables balance as of March 31, 2018 or December 31, 2017.
Revenue allocated to remaining performance obligations	$ 589.5
Percentage of revenue allocated to remaining performance obligations to be recognized over the next 12 months	50.00%
Capitalized sales commissions minimum amortization period	1 year
Selling and Marketing [Member]
Revenue [Line Items]
Amortization of capitalized sales commissions	$ 2.3
Cost of Revenue [Member]
Revenue [Line Items]
Amortization of capitalized contract costs	1.2
Other Noncurrent Assets [Member]
Revenue [Line Items]
Capitalized sales commissions	19.1
Capitalized contract costs, noncurrent	12.0
Other Current Assets [Member]
Revenue [Line Items]
Capitalized sales commissions	0.4
Capitalized contract costs, current	$ 0.2