Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	2 Months Ended	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)		$ 20	$ 15	$ 89	$ (3,020)
U.S. federal corporate tax rate	34.00%			21.00%
Reduction of valuation allowance attributable to deferred tax assets				$ 2,000
IPR&D
Operating Loss Carryforwards [Line Items]
Reduction in deferred tax liability				$ 1,000