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