Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Oct. 31, 2021	Jul. 31, 2021	Oct. 31, 2020	Jul. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
Before Tax:
Net other comprehensive income (loss)		$ 10		$ 21		$ 26	$ 24
Tax Effect:
Net other comprehensive income (loss)		(8)		(6)		(16)	15
Net of Tax:
Net other comprehensive income (loss)		2	$ 8	15	$ 24	10	39
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Before Tax:
Net gain (loss)		(9)		5		(17)	58
Reclassification to earnings		0		0		0	0
Net other comprehensive income (loss)		(9)		5		(17)	58
Tax Effect:
Net gain (loss)		(3)		(1)		(5)	8
Reclassification to earnings		0		0		0	0
Net other comprehensive income (loss)		(3)		(1)		(5)	8
Net of Tax:
Net gain (loss)		(12)		4		(22)	66
Reclassification to earnings		0		0		0	0
Net other comprehensive income (loss)		(12)		4		(22)	66
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Before Tax:
Net gain (loss)		15		14		30	(35)
Reclassification to earnings	[1]	(2)		(5)		1	(16)
Net other comprehensive income (loss)		13		9		31	(51)
Tax Effect:
Net gain (loss)		(4)		(4)		(7)	8
Reclassification to earnings	[1]	1		1		0	4
Net other comprehensive income (loss)		(3)		(3)		(7)	12
Net of Tax:
Net gain (loss)		11		10		23	(27)
Reclassification to earnings	[1]	(1)		(4)		1	(12)
Net other comprehensive income (loss)		10		6		24	(39)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Before Tax:
Net gain (loss)		(1)		0		(1)	0
Reclassification to earnings	[2]	7		7		13	17
Net other comprehensive income (loss)		6		7		12	17
Tax Effect:
Net gain (loss)		0		0		0	0
Reclassification to earnings	[2]	(2)		(2)		(4)	(5)
Net other comprehensive income (loss)		(2)		(2)		(4)	(5)
Net of Tax:
Net gain (loss)		(1)		0		(1)	0
Reclassification to earnings	[2]	5		5		9	12
Net other comprehensive income (loss)		$ 4		$ 5		$ 8	12
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 six months ended October 31, 2020, $4 of the pre-tax amount of $17 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.