Long-term Debt - Interest Expense Related to Convertible Notes (Detail) - Convertible notes - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Schedule Of Interest Expenses [Line Items]
Contractual interest expense	$ 1,813	$ 1,857
Amortization of debt discount	2,159	1,965
Amortization of debt issuance cost	37	34
Total interest expense	$ 4,009	$ 3,856