Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Narrative (Details)

v3.8.0.1
Fair Value Measurements - Narrative (Details)
$ / shares in Units, shares in Thousands
12 Months Ended
Dec. 31, 2017
USD ($)
class_of_stock
$ / shares
shares
Dec. 31, 2016
USD ($)
class_of_stock
Dec. 31, 2015
Level 3 Valuation      
Number of changes in valuation techniques | class_of_stock 0 0  
Amount of transfers of assets from level 2 to level 1 $ 0 $ 0  
Amount of transfers of assets from level 1 to level 2 $ 0 $ 0  
Common stock warrants      
Level 3 Valuation      
Number of shares available under warrant (in shares) | shares 40    
Minimum      
Level 3 Valuation      
Expected life 5 years 5 years 5 years
Maximum      
Level 3 Valuation      
Expected life 6 years 3 months 6 years 3 months 6 years 3 months
Level 2      
Level 3 Valuation      
Estimated fair value of debt   $ 2,400,000  
Level 3      
Level 3 Valuation      
Change in fair value $ 29,624 (72,625)  
Warrant liability | Level 3      
Level 3 Valuation      
Volatility 55.00%    
Risk free interest rate 1.96%    
Strike price (in dollars per share) | $ / shares $ (8.40)    
Share price (in dollars per share) | $ / shares $ (3.20)    
Expected life 2 years 9 months 18 days    
Change in fair value $ 2,684 (22,105)  
Equity Unit Purchase Option | Level 3      
Level 3 Valuation      
Strike price (in dollars per share) | $ / shares $ (7.48)    
Change in fair value $ 26,940 $ (50,520)  
Equity Unit Purchase Option | Level 3 | Class A Warrant      
Level 3 Valuation      
Strike price (in dollars per share) | $ / shares $ (5.23)    
Equity Unit Purchase Option | Level 3 | Class B Warrant      
Level 3 Valuation      
Strike price (in dollars per share) | $ / shares $ (4.49)    
Equity Unit Purchase Option | Level 3 | Minimum      
Level 3 Valuation      
Volatility 40.00%    
Risk free interest rate 1.28%    
Equity Unit Purchase Option | Level 3 | Maximum      
Level 3 Valuation      
Volatility 50.00%    
Risk free interest rate 2.17%