Annual report pursuant to Section 13 and 15(d)

Investment in Viking - Narrative (Details)

v3.8.0.1
Investment in Viking - Narrative (Details)
$ / shares in Units, $ in Thousands
1 Months Ended 9 Months Ended 12 Months Ended 13 Months Ended
Apr. 13, 2016
USD ($)
shares
Apr. 30, 2016
USD ($)
$ / shares
shares
May 31, 2015
USD ($)
$ / shares
shares
May 31, 2014
USD ($)
program
Dec. 31, 2016
USD ($)
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
May 31, 2015
$ / shares
Jul. 31, 2017
USD ($)
May 31, 2017
Jan. 31, 2016
USD ($)
Aug. 31, 2014
$ / shares
shares
Variable Interest Entity [Line Items]                          
Warrants to purchase shares (shares) | shares                         3,264,643
Exercise price of warrants (USD per share) | $ / shares                         $ 125.08
Proceeds received from repayment of Viking note receivable           $ 200 $ 300 $ 0          
Note receivable from Viking         $ 3,207 $ 3,877 $ 3,207            
Viking                          
Variable Interest Entity [Line Items]                          
Number of programs licensed | program       5                  
Loss recorded (as a percent)                 100.00%        
Debt | Viking                          
Variable Interest Entity [Line Items]                          
Convertible loan facility extended       $ 2,500                  
Repayment in equity (as a percent)   200.00%                      
Equity Method Investee                          
Variable Interest Entity [Line Items]                          
Shares sold in Viking IPO (shares) | shares   7,500,000                      
Initial offering price (USD per share) | $ / shares   $ 1.25                      
Shares of Viking stock purchased (shares) | shares   560,000                      
Purchase of Viking common stock   $ 700                      
Interest rate on note due from Viking (as a percent)                     2.50% 5.00%  
Extension of lock-up period   1 year                      
Amount of loan to be repaid upon consummation of first capital financing transaction                       $ 1,500  
Amount of loan to be repaid in cash upon consummation of first capital financing transaction                   $ 200      
Warrants to purchase shares (shares) | shares   7,500,000                      
Exercise price of warrants (USD per share) | $ / shares   $ 1.50                      
Warrants purchased (shares) | shares   560,000                      
Proceeds received from repayment of Viking note receivable $ 300                        
Shares received pursuant to MLA amendment (shares) | shares 960,000                        
Warrants received, licensing agreement (shares) | shares 960,000                        
Value of consideration received for repayment of convertible notes $ 1,200                        
Aggregate ownership (as a percent)   32.70%     30.30% 17.60% 30.30%            
Increase (decrease) in equity method investment         $ (10,700) $ 2,700              
Other than temporary impairment of investment in Viking             $ 7,400            
Common Stock                          
Variable Interest Entity [Line Items]                          
Aggregate value of shares received in Viking IPO     $ 29,200                    
Shares of Viking stock purchased (shares) | shares     1,100,000                    
Purchase of Viking common stock     $ 9,000                    
Common Stock | Equity Method Investee | IPO                          
Variable Interest Entity [Line Items]                          
Shares sold in Viking IPO (shares) | shares     3,700,000                    
Aggregate offering price     $ 29,200                    
Initial offering price (USD per share) | $ / shares     $ 8.00           $ 8.00        
Warrants                          
Variable Interest Entity [Line Items]                          
Gain on changes in fair value           $ 3,200 $ 300