Income Taxes - Valuation Allowance of Gross Deferred Tax Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2017
Valuation allowance against gross deferred tax assets:
Valuation allowance, beginning balance	$ 142,650	$ 185,898	$ 1,489,780
Additions	27,459	23,720	0
Deductions	34,131	66,968	1,303,882
Valuation allowance, ending balance	$ 135,978	$ 142,650	$ 185,898