Other Comprehensive Income Schedule of Other Comprehensive Income (Details) - USD ($) $ in Millions		12 Months Ended
		Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Before Tax:
Net other comprehensive income (loss)		$ 108	$ (151)	$ 39
Tax Effect:
Net other comprehensive income (loss)		17	10	(24)
Net of Tax:
Net other comprehensive income (loss)		125	(141)	15
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Before Tax:
Net gain (loss)		106	(88)	(16)
Reclassification to earnings		0	0	0
Net other comprehensive income (loss)		106	(88)	(16)
Tax Effect:
Net gain (loss)		17	(6)	(11)
Reclassification to earnings		0	0	0
Net other comprehensive income (loss)		17	(6)	(11)
Net of Tax:
Net gain (loss)		123	(94)	(27)
Reclassification to earnings		0	0	0
Net other comprehensive income (loss)		123	(94)	(27)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Before Tax:
Net gain (loss)		(78)	61	69
Reclassification to earnings	[1]	(21)	(23)	(6)
Net other comprehensive income (loss)		(99)	38	63
Tax Effect:
Net gain (loss)		17	(14)	(16)
Reclassification to earnings		6	6	1
Net other comprehensive income (loss)		23	(8)	(15)
Net of Tax:
Net gain (loss)		(61)	47	53
Reclassification to earnings		(15)	(17)	(5)
Net other comprehensive income (loss)		(76)	30	48
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Before Tax:
Net gain (loss)		71	(119)	(41)
Reclassification to earnings	[2]	30	18	33
Net other comprehensive income (loss)		101	(101)	(8)
Tax Effect:
Net gain (loss)		(16)	28	10
Reclassification to earnings		(7)	(4)	(8)
Net other comprehensive income (loss)		(23)	24	2
Net of Tax:
Net gain (loss)		55	(91)	(31)
Reclassification to earnings		23	14	25
Net other comprehensive income (loss)		78	$ (77)	$ (6)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] | Gain on sale of business
Before Tax:
Reclassification to earnings		$ 4

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

[2] For the year ended April 30, 2021, $4 of the pre-tax amount of $30 is classified in gain on sale of business in the accompanying consolidated statements of operations. Otherwise, the pre-tax amount for each year is classified as non-operating postretirement expense.