Other Disclosures - Contingent liabilities (Details) - Aditech - USD ($)
$ in Millions
1 Months Ended 12 Months Ended
May 31, 2017
Dec. 31, 2017
Contingent liabilities    
Obligation payable   $ 25
Addendum    
Contingent liabilities    
Percentage due of non refundable fee   2.00%
Obligation payable   $ 25
Contingent liability paid $ 25  
Exclusive license    
Contingent liabilities    
Percentage Royalty Due Contingent Liability   2.00%
Co-exclusive license    
Contingent liabilities    
Percentage Royalty Due Contingent Liability   20.00%
Co-exclusive rights to develop    
Contingent liabilities    
Percentage Royalty Due Contingent Liability   2.00%