Convertible Senior Notes - Carrying Values of Notes Excluding the Discounts upon Original Issuance and Third Party Offering Costs (Detail) - Convertible Senior Notes Due 2020 [Member] - USD ($) $ in Thousands	Apr. 30, 2016	Jan. 30, 2016	Jun. 30, 2015
Liability component
Principal	$ 300,000	$ 300,000
Less: Debt discount	(71,456)	(75,113)	$ (3,800)
Net carrying amount	228,544	224,887
Equity component	$ 84,003	$ 84,003