Fair Value - Schedule of Changes in Fair Value of Level 3 Financial Instruments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative liability of embedded conversion feature	$ 24,414	$ 11,587
Beginning Balance	24,414	11,587
Change in fair value	7,079	10,287
Ending Balance	35,623	24,414
Bridge Notes [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative liability of embedded conversion feature	221	221
Beginning Balance	221
Ending Balance	377	221
Reimbursement Notes [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative liability of embedded conversion feature	47	47
Beginning Balance	47
Ending Balance	105	47
Convertible Notes [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative liability of embedded conversion feature	2,272	2,272
Beginning Balance	2,272
Ending Balance	$ 3,648	$ 2,272