Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Jul. 31, 2018	Oct. 31, 2017
Deferred tax assets:
Reserves and accrued liabilities	$ 35,022	$ 56,597
Depreciation and amortization	317,526	451,385
NOL and credit carry forward	496,327	803,622
Other	20,077	29,398
Gross deferred tax assets	868,952	1,341,002
Valuation allowance	(144,865)	(185,898)
Deferred tax asset, net of valuation allowance	$ 724,087	$ 1,155,104