v3.20.2
Debt - Additional Information (Details)
3 Months Ended 9 Months Ended
Jun. 25, 2020
USD ($)
Apr. 23, 2020
USD ($)
day
$ / shares
Sep. 30, 2020
USD ($)
agreement
Jun. 30, 2020
USD ($)
Sep. 30, 2019
USD ($)
Sep. 30, 2020
USD ($)
agreement
Sep. 30, 2019
USD ($)
Dec. 31, 2019
USD ($)
May 22, 2019
USD ($)
Debt Instrument [Line Items]                  
Proceeds from debt           $ 371,681,000 $ 243,726,000    
Purchases of capped calls in connection with convertible senior notes       $ 50,540,000          
Loss on debt extinguishment   $ 11,700,000 $ 0   $ 0 11,671,000 $ 0    
Deferred financing costs     $ 116,352,000     $ 116,352,000   $ 7,238,000  
Number of contracts (in contracts) | agreement     2     2      
Deferred government grant obligations     $ 3,500,000     $ 3,500,000      
Prince George's County, Maryland                  
Debt Instrument [Line Items]                  
Interest rate     3.00%     3.00%      
Deferred government grant obligations                  
Debt Instrument [Line Items]                  
Interest payable     $ 400,000     $ 400,000   $ 300,000  
Convertible senior notes                  
Debt Instrument [Line Items]                  
Fair value     547,200,000     547,200,000      
The Notes | Convertible senior notes                  
Debt Instrument [Line Items]                  
Aggregate principal amount   380,000,000              
Proceeds from debt   $ 369,600,000              
Interest rate   2.25%              
Debt issuance costs     $ 7,300,000     $ 12,300,000      
Debt instrument, effective interest rate percentage     11.20%     10.80%      
Debt instrument, convertible, carrying Amount   $ 117,800,000              
Debt instrument, convertible, threshold percentage of stock price trigger   130.00%              
Debt instrument, convertible, threshold trading days | day   20              
Debt instrument, convertible, threshold consecutive trading days | day   30              
Debt instrument, convertible, threshold consecutive trading days, sale price per share | day   5              
Debt instrument, convertible, measurement period | day   10              
Debt instrument, threshold percentage of sales price per share   98.00%              
Debt instrument, convertible, conversion ratio   0.0353773              
Debt instrument, convertible, conversion price (in dollars per share) | $ / shares   $ 28.27              
Capped call, cap price (in dollars per share) | $ / shares   $ 44.34              
Purchases of capped calls in connection with convertible senior notes   $ 50,500,000              
The Notes | Convertible senior notes | Measurement Input, Discount Rate                  
Debt Instrument [Line Items]                  
Debt instrument, discount rate   0.103              
Credit Agreement | Letter of Credit                  
Debt Instrument [Line Items]                  
Aggregate principal amount                 $ 250,000,000
Maximum borrowing capacity $ 50,000,000   $ 50,000,000.0     $ 50,000,000.0      
Debt instrument, principal amount of the lenders' commitments, maximum $ 100,000,000                
Outstanding amount under credit agreement     $ 0     $ 0      
Repayments of Debt   $ 250,000,000              
Interest payable   1,300,000              
Deferred financing costs   9,200,000              
Prepayment premium   $ 2,500,000              
Credit Agreement | Letter of Credit | LIBOR                  
Debt Instrument [Line Items]                  
Variable rate, applicable margin 3.75%                
Credit Agreement | Letter of Credit | LIBOR | Minimum                  
Debt Instrument [Line Items]                  
Variable rate, applicable margin 0.00%                
Credit Agreement | Letter of Credit | Base rate                  
Debt Instrument [Line Items]                  
Variable rate, applicable margin 2.75%