Fair Value Measurement - Summary of Fair Value Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative liability - embedded conversion feature	$ 58,261	$ 120,848	[1]
Level 3
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative liability - embedded conversion feature	$ 58,261	$ 120,848

[1] Balances derived from audited financial statements as of December 31, 2015.