Summary of Significant Accounting Policies - Recently Adopted Accounting Standards (Details) - USD ($) $ in Millions		6 Months Ended
	Nov. 01, 2019	Apr. 30, 2020	Oct. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of stranded tax effects	$ 189	$ (189)
Operating lease right of use assets		121	$ 0
Operating Lease, Liability		$ 124
Accounting Standards Update 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of stranded tax effects	189
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right of use assets	111
Operating Lease, Liability	$ 114