Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Financial Instruments Measured at Fair Value on Recurring Basis (Detail)

v3.3.1.900
Fair Value Measurements - Financial Instruments Measured at Fair Value on Recurring Basis (Detail) - USD ($)
$ in Thousands
Dec. 31, 2015
Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Securities   $ 20,002
Long-term investments, at fair value $ 2,485 4,160
Total   24,162
US Treasury Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Securities   19,998
Money Market Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Securities   4
Warrant [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative warrant liability 114  
Fair Value, Inputs, Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Securities   20,002
Long-term investments, at fair value 0 0
Total   20,002
Fair Value, Inputs, Level 1 [Member] | US Treasury Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Securities   19,998
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Securities   4
Fair Value, Inputs, Level 1 [Member] | Warrant [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative warrant liability 0  
Fair Value, Inputs, Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Securities   0
Long-term investments, at fair value 0 0
Total   0
Fair Value, Inputs, Level 2 [Member] | US Treasury Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Securities   0
Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Securities   0
Fair Value, Inputs, Level 2 [Member] | Warrant [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative warrant liability 0  
Fair Value, Inputs, Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Securities   0
Long-term investments, at fair value 2,485 4,160
Total   4,160
Fair Value, Inputs, Level 3 [Member] | US Treasury Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Securities   $ 0
Fair Value, Inputs, Level 3 [Member] | Warrant [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative warrant liability $ 114