Long-term Debt - Outstanding Convertible Note Balances (Detail) - Convertible notes - USD ($)	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2014
Convertible Debt [Line Items]
Principal	$ 200,000,000	$ 200,000,000	$ 200,000,000.0
Less: debt discount and unamortized debt issuance costs	(33,365,000)	(35,562,000)
Net carrying amount	166,635,000	164,438,000
Equity component	$ 40,896,000	$ 40,896,000