Convertible Senior Notes - Carrying Value of Notes Excluding the Discounts and Commissions Payable to the Initial Purchasers and Third Party Offering Costs (Detail) - Convertible Senior Notes Due 2019 [Member] - USD ($) $ in Thousands	Nov. 03, 2018	Feb. 03, 2018	Jun. 30, 2014
Liability component
Principal	$ 350,000	$ 350,000
Less: Debt discount	(9,701)	(20,988)	$ (4,400)
Net carrying amount	340,299	329,012
Equity component	$ 70,482	$ 70,482