Information Pertaining to 2017 Notes (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($)
Debt Instrument [Line Items]
Beginning Balance	$ 21,565
2017 Notes
Debt Instrument [Line Items]
Beginning Balance	21,565
Loss from change in fair value of debt	1,775
Ending Balance	23,340
2017 Notes | Principal Amount
Debt Instrument [Line Items]
Beginning Balance	26,108
Ending Balance	26,108
2017 Notes | Change in Estimated Fair Value
Debt Instrument [Line Items]
Beginning Balance	(4,543)
Loss from change in fair value of debt	1,775
Ending Balance	$ (2,768)