Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended
		Jul. 31, 2021	Jul. 31, 2020
Before Tax:
Net other comprehensive income (loss)		$ 16	$ 3
Tax Effect:
Net other comprehensive income (loss)		(8)	21
Net of Tax:
Net other comprehensive income (loss)		8	24
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Before Tax:
Net gain (loss)		(8)	53
Reclassification to earnings		0	0
Net other comprehensive income (loss)		(8)	53
Tax Effect:
Net gain (loss)		(2)	9
Reclassification to earnings		0	0
Net other comprehensive income (loss)		(2)	9
Net of Tax:
Net gain (loss)		(10)	62
Reclassification to earnings		0	0
Net other comprehensive income (loss)		(10)	62
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Before Tax:
Net gain (loss)		15	(49)
Reclassification to earnings	[1]	3	(11)
Net other comprehensive income (loss)		18	(60)
Tax Effect:
Net gain (loss)		(3)	12
Reclassification to earnings	[1]	(1)	3
Net other comprehensive income (loss)		(4)	15
Net of Tax:
Net gain (loss)		12	(37)
Reclassification to earnings	[1]	2	(8)
Net other comprehensive income (loss)		14	(45)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Before Tax:
Net gain (loss)		0	0
Reclassification to earnings	[2]	6	10
Net other comprehensive income (loss)		6	10
Tax Effect:
Net gain (loss)		0	0
Reclassification to earnings	[2]	(2)	(3)
Net other comprehensive income (loss)		(2)	(3)
Net of Tax:
Net gain (loss)		0	0
Reclassification to earnings	[2]	4	7
Net other comprehensive income (loss)		$ 4	7
Gain on sale of business [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Before Tax:
Reclassification to earnings			$ 4

[1] Pre-tax amount for each period is classified as sales in the accompanying condensed consolidated statements of operations.

[2] For the three months ended July 31, 2020, $4 of the pre-tax amount of $10 is classified in gain on sale of business in the accompanying condensed consolidated statements of operations. Otherwise, the pre-tax amount for each period is classified as non-operating postretirement expense.