Finance Receivables - Narrative (Details) $ in Millions	Apr. 30, 2018 USD ($) segments	Jan. 31, 2018 segments	Oct. 31, 2017 USD ($)
Schedule of Securitization [Line Items]
Loans and Leases Receivable, Net Amount	$ 1,900		$ 1,800
Number of Portfolio Segments for Finance Receivables | segments	2	2
Trac Funding Facility [Member]
Schedule of Securitization [Line Items]
Finance Receivables Retail Accounts Collateral For Borrowed Securities	$ 805		797
Cash Collateral for Borrowed Securities	238		163
Financial Services Operations
Schedule of Securitization [Line Items]
Assets Net Of Intercompany Balances	$ 2,300		$ 2,200