Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	2 Months Ended	3 Months Ended		9 Months Ended		10 Months Ended
	Dec. 31, 2017	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017	Oct. 31, 2018
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)		$ 15	$ (1)	$ (3,020)	$ 44
U.S. federal corporate tax rate	34.00%
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
Scenario Plan [Member]
Operating Loss Carryforwards [Line Items]
U.S. federal corporate tax rate						21.00%