Other Comprehensive Income Schedule of Other Comprehensive Income (Details) - USD ($) $ in Millions		12 Months Ended
		Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
Before Tax:
Net other comprehensive income (loss)		$ (151)	$ 39	$ (6)
Tax Effect:
Net other comprehensive income (loss)		10	(24)	18
Net of Tax:
Net other comprehensive income (loss)		(141)	15	12
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Before Tax:
Net gain (loss)		(88)	(16)	12
Reclassification to earnings		0	0	0
Net other comprehensive income (loss)		(88)	(16)	12
Tax Effect:
Net gain (loss)		(6)	(11)	12
Reclassification to earnings		0	0	0
Net other comprehensive income (loss)		(6)	(11)	12
Net of Tax:
Net gain (loss)		(94)	(27)	24
Reclassification to earnings		0	0	0
Net other comprehensive income (loss)		(94)	(27)	24
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Before Tax:
Net gain (loss)		61	69	(54)
Reclassification to earnings	[1]	(23)	(6)	11
Net other comprehensive income (loss)		38	63	(43)
Tax Effect:
Net gain (loss)		(14)	(16)	18
Reclassification to earnings	[1]	6	1	(3)
Net other comprehensive income (loss)		(8)	(15)	15
Net of Tax:
Net gain (loss)		47	53	(36)
Reclassification to earnings	[1]	(17)	(5)	8
Net other comprehensive income (loss)		30	48	(28)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Before Tax:
Net gain (loss)		(119)	(41)	5
Reclassification to earnings	[2]	18	33	20
Net other comprehensive income (loss)		(101)	(8)	25
Tax Effect:
Net gain (loss)		28	10	(2)
Reclassification to earnings	[2]	(4)	(8)	(7)
Net other comprehensive income (loss)		24	2	(9)
Net of Tax:
Net gain (loss)		(91)	(31)	3
Reclassification to earnings	[2]	14	25	13
Net other comprehensive income (loss)		$ (77)	$ (6)	$ 16

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

[2] Pre-tax amount is classified as non-operating postretirement expense in the accompanying consolidated statements of operations.