Accounting Policies Adoption of updated accounting standards (Details) - USD ($) $ in Millions	May 01, 2019	Apr. 30, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Liability		$ 53
Operating Lease, Right-of-Use Asset		$ 51
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Liability	$ 54
Operating Lease, Right-of-Use Asset	54
Accounting Standards Update 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect	$ 43