XML 36 R26.htm IDEA: XBRL DOCUMENT v3.10.0.1
Description of Business (Details)
 1 Months Ended 3 Months Ended 9 Months Ended
Sep. 30, 2018
USD ($)
medicine
program
Sep. 30, 2018
USD ($)
medicine
program
Mar. 31, 2018
USD ($)
shares
Sep. 30, 2018
USD ($)
medicine
program
Sep. 30, 2017
USD ($)
Oct. 08, 2018
program
Dec. 31, 2017
USD ($)
Business Acquisition [Line Items]              
Number of approved medicines for Fabry disease | medicine 1 1   1      
Number of gene therapy programs | program 14 14   14      
Number of gene therapy programs for Batten disease | program 2 2   2      
Number of gene therapy programs for neurologic LSDs developed | program 10            
Common stock issued from underwriting agreement (in shares) | shares     20,239,839        
Proceeds from issuance of common stock, net of issuance costs     $ 294,600,000 $ 294,584,000 $ 243,036,000    
Retained earnings (accumulated deficit) $ 1,334,141,000 $ 1,334,141,000   1,334,141,000     $ 1,063,610,000
Line of Credit              
Business Acquisition [Line Items]              
New credit facility borrowing capacity 150,000,000 $ 150,000,000   $ 150,000,000      
Debt instrument term   5 years          
Proceeds from issuance of debt 146,600,000            
Line of Credit | LIBOR              
Business Acquisition [Line Items]              
Basis spread on variable rate   7.50%          
Subsequent Event              
Business Acquisition [Line Items]              
Number of gene therapy programs | program           4  
Celenex              
Business Acquisition [Line Items]              
Research and development expense $ 100,000,000