Long-term Debt - Net Carrying Amount of Equity Component of Convertible Debt (Detail) - 1.75% Convertible Senior Notes due 2021 [Member] - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016
Debt Instrument [Line Items]
Net carrying amount			$ 32,900
Debt, Equity Component [Member]
Debt Instrument [Line Items]
Debt discount related to value of conversion option	$ 32,945	$ 32,945
Debt issuance cost	(1,179)	(1,179)
Net carrying amount	$ 31,766	$ 31,766