Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended
		Jul. 31, 2019	Jul. 31, 2018
Before Tax:
Net other comprehensive income (loss)		$ 7	$ 28
Tax Effect:
Net other comprehensive income (loss)		(8)	(14)
Net of Tax:
Net other comprehensive income (loss)		(1)	14
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Before Tax:
Net gain (loss)		(8)	(5)
Reclassification to earnings		0	0
Net other comprehensive income (loss)		(8)	(5)
Tax Effect:
Net gain (loss)		(5)	(7)
Reclassification to earnings		0	0
Net other comprehensive income (loss)		(5)	(7)
Net of Tax:
Net gain (loss)		(13)	(12)
Reclassification to earnings		0	0
Net other comprehensive income (loss)		(13)	(12)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Before Tax:
Net gain (loss)		15	27
Reclassification to earnings	[1]	(4)	2
Net other comprehensive income (loss)		11	29
Tax Effect:
Net gain (loss)		(3)	(6)
Reclassification to earnings	[1]	1	0
Net other comprehensive income (loss)		(2)	(6)
Net of Tax:
Net gain (loss)		12	21
Reclassification to earnings	[1]	(3)	2
Net other comprehensive income (loss)		9	23
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Before Tax:
Net gain (loss)		0	0
Reclassification to earnings	[2]	4	4
Net other comprehensive income (loss)		4	4
Tax Effect:
Net gain (loss)		0	0
Reclassification to earnings	[2]	(1)	(1)
Net other comprehensive income (loss)		(1)	(1)
Net of Tax:
Net gain (loss)		0	0
Reclassification to earnings	[2]	3	3
Net other comprehensive income (loss)		$ 3	$ 3

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

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