XML 109 R80.htm IDEA: XBRL DOCUMENT v3.19.1
Fair Value of Financial Instruments - Schedule of Inputs of the Black-Scholes Option Pricing Model (Details) - Black-Scholes option pricing model - Level 3
Dec. 31, 2017
$ / shares
Dec. 31, 2015
$ / shares
Dec. 31, 2014
$ / shares
Weichai warrant liability      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Contractual term 1 year    
Private placement warranty liability      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Contractual term   6 months 29 days 1 year 4 months
Market value of the Common Stock | Weichai warrant liability      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Option pricing model input 7.50    
Market value of the Common Stock | Private placement warranty liability      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Option pricing model input   18.25 51.61
Exercise price | Private placement warranty liability      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Option pricing model input   13.00 13.00
Risk-free interest rate | Weichai warrant liability      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Option pricing model input 0.018    
Estimated price volatility | Weichai warrant liability      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Option pricing model input 0.95    
Estimated price volatility | Private placement warranty liability      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Option pricing model input   0.55 0.55
Dividend yield | Weichai warrant liability      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Option pricing model input 0