Stockholders' Equity Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Jul. 31, 2020	Jul. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (547)
Net other comprehensive income (loss)	24	$ (1)
Ending balance	(523)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(302)
Net other comprehensive income (loss)	62	(13)
Ending balance	(240)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	60
Net other comprehensive income (loss)	(45)	9
Ending balance	15
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(305)
Net other comprehensive income (loss)	7	3
Ending balance	(298)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net other comprehensive income (loss)	$ 24	$ (1)