Summary of Significant Accounting Policies - Variable Interest Entities (Details) - USD ($) $ in Millions	Jul. 31, 2018	Oct. 31, 2017
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 1,022	$ 706
Variable Interest Entity Primary Beneficiary, Blue Diamond Parts [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	43	49
Cash and cash equivalents	2	10
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	6	13
Variable Interest Entity Primary Beneficiary Securitizations Treated As Borrowings [Member] | Financial Services Operations
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	949	869
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	812	754
Transaction Does Not Qualify for Sale Accounting [Member] | Financial Services Operations
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	311	278
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	$ 184	$ 194