Business Combinations - Additional Information (Detail) (Endace Limited, USD $) In Millions, unless otherwise specified	0 Months Ended	1 Months Ended
	Apr. 25, 2013	Feb. 26, 2013	Apr. 25, 2013
Endace Limited
Business Combinations [Line Items]
Date of acquisition		Feb. 26, 2013
Percentage of outstanding common stock acquired		89.60%	100.00%
Cash consideration of acquisition	$ 122.4	$ 110.4
Business Acquisition Cost Of Acquired Entity Additional Cash Paid			$ 12.0