Outstanding Convertible Note Balances (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Jun. 30, 2014
Convertible Debt [Line Items]
Net carrying amount	$ 164,438	$ 156,154
Senior Notes
Convertible Debt [Line Items]
Principal	200,000	200,000	$ 200,000
Less: debt discount and unamortized debt issuance costs	(35,562)	(43,846)
Net carrying amount	164,438	156,154
Equity component	$ 40,896	$ 40,896