Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail)

v3.3.1.900
Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)
$ in Thousands
Dec. 31, 2015
Dec. 31, 2014
Assets    
Total assets $ 55,458 $ 47,308
Warrant [Member]    
Liabilities    
Liabilities 1,105 3,002
Cash [Member]    
Assets    
Total assets 14,034 16,481
Money market securities (cash equivalents) [Member]    
Assets    
Total assets 20,276 11,416
Restricted cash [Member]    
Assets    
Total assets 272 251
Corporate bonds and commercial paper [Member]    
Assets    
Total assets 20,876 19,160
Level 1 [Member]    
Assets    
Total assets 34,582 28,148
Level 1 [Member] | Cash [Member]    
Assets    
Total assets 14,034 16,481
Level 1 [Member] | Money market securities (cash equivalents) [Member]    
Assets    
Total assets 20,276 11,416
Level 1 [Member] | Restricted cash [Member]    
Assets    
Total assets 272 251
Level 2 [Member]    
Assets    
Total assets 20,876 19,160
Level 2 [Member] | Corporate bonds and commercial paper [Member]    
Assets    
Total assets 20,876 19,160
Level 3 [Member] | Warrant [Member]    
Liabilities    
Liabilities $ 1,105 $ 3,002