Summary of Total Interest Expense Recognized (Detail) - 0.25% Convertible Senior Note Due 2022 - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Dec. 31, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
0.25% contractual coupon	$ 219	$ 297
Amortization of debt discount and debt issuance costs including initial purchaser discount	2,935	4,043
Interest expense	$ 3,154	$ 4,340