Long-term Debt - Outstanding Convertible Note Balances (Detail) - Convertible notes, net - USD ($)	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2014
Debt Instrument [Line Items]
Principal	$ 200,000,000	$ 200,000,000	$ 200,000,000.0
Less: debt discount and unamortized debt issuance costs	(31,116,000)	(35,562,000)
Net carrying amount	168,884,000	164,438,000
Equity component	$ 40,896,000	$ 40,896,000