Income Taxes - Additional Information (Details) - USD ($)
 2 Months Ended 12 Months Ended
Dec. 31, 2017
Oct. 31, 2020
Oct. 31, 2019
Oct. 31, 2018
Operating Loss Carryforwards [Line Items]        
Income tax expense (benefit)   $ 46,000 $ 109,000 $ (3,015,000)
U.S. federal corporate tax rate 34.00% 21.00% 21.00% 23.20%
Reduction of valuation allowance attributable to deferred tax assets   $ 2,000,000.0    
Franchise tax expense   300,000 $ 200,000 $ 500,000
Federal Operating Loss Carryforwards   905,400,000    
State Operating Loss Carryforwards   457,100,000    
Tax Credits, State   12,500,000    
Deferred tax assets, gross   146,461,000 253,000,000  
Unrecognized Tax Benefits   0.0 15,700,000  
Unrecognized tax benefits, provision for interest or penalties   0 $ 0  
Federal [Member]        
Operating Loss Carryforwards [Line Items]        
Federal net operating loss carryforward   325,600,000    
Deferred tax assets, gross   $ 68,400,000    
Federal [Member] | Minimum [Member]        
Operating Loss Carryforwards [Line Items]        
Tax Credit Carryforward, Expiration Date   Jan. 01, 2021    
Federal [Member] | Maximum [Member]        
Operating Loss Carryforwards [Line Items]        
Tax Credit Carryforward, Expiration Date   Jan. 01, 2038    
State [Member]        
Operating Loss Carryforwards [Line Items]        
Deferred tax assets, gross   $ 26,400,000    
State net operating loss carryforward   $ 431,800,000    
State [Member] | Minimum [Member]        
Operating Loss Carryforwards [Line Items]        
Tax Credit Carryforward, Expiration Date   Jan. 01, 2021    
State [Member] | Maximum [Member]        
Operating Loss Carryforwards [Line Items]        
Tax Credit Carryforward, Expiration Date   Jan. 01, 2038    
In Process Research And Development [Member]        
Operating Loss Carryforwards [Line Items]        
Reduction in deferred tax liability   $ 1,000,000.0