Summary of Significant Accounting Policies - Variable Interest Entities (Details) - USD ($) $ in Millions	Jul. 31, 2020	Oct. 31, 2019
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	$ 6,675	$ 6,917
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	10,503	10,640
Cash and cash equivalents	1,648	1,370
Financial Services Operations
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	2,285	2,774
Variable Interest Entity, Primary Beneficiary [Member] | Variable Interest Entity Primary Beneficiary, Blue Diamond Parts [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	23	32
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	5	4
Cash and cash equivalents	5	2
Variable Interest Entity, Primary Beneficiary [Member] | 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	973	927
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	900	838
Variable Interest Entity, Primary Beneficiary [Member] | Transaction Does Not Qualify for Sale Accounting [Member] | Financial Services Operations
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	293	537
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	$ 216	$ 279