Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Oct. 31, 2017
Deferred tax assets:
Reserves and accrued liabilities	$ 36,115	$ 56,597
Depreciation and amortization	288,145	451,385
NOL and credit carry forward	538,869	803,622
Other	18,706	29,398
Gross deferred tax assets	881,835	1,341,002
Valuation allowance	(147,011)	(185,898)
Deferred tax asset, net of valuation allowance	$ 734,824	$ 1,155,104