Accumulated Other Comprehensive Income Schedule of Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2015
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax		$ (30)	$ (65)	$ (57)	$ (113)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax		0	3	(1)	5
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax		(30)	(62)	(58)	(108)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax		29	71	74	118
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax		(11)	(28)	(26)	(45)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax		18	43	48	73
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	[1]	(17)	(16)	(46)	(20)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax	[1]	7	7	18	8
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	[1]	(10)	(9)	(28)	(12)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) and Net Prior Service Credit (Cost) Arising During Period, before Tax		0	0	0	14
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) and Net Prior Service Credit (Cost) Arising During Period, Tax		0	0	0	(5)
Other Comprehensive Income Defined Benefit Plan Actuarial Gain Loss And Net Prior Service Costs Credit Arising During Period Net Of Tax		0	0	0	9
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss) and Net Prior Service Credit (Cost), before Tax	[2]	7	6	23	18
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net (Gain) Loss and Prior Service (Credit) Cost, Tax	[2]	(2)	(2)	(8)	(7)
Other Comprehensive Income Reclassification Of Actuarial Gain Loss And Prior Service Cost Net Of Tax	[2]	5	4	15	11
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent		(11)	(4)	(6)	17
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent		(6)	(20)	(17)	(44)
Other Comprehensive Income (Loss), Net of Tax		$ (17)	$ (24)	$ (23)	$ (27)

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

[2] 2Pre-tax amount is a component of pension and other postretirement benefit expense (as shown in Note 7, except for amounts related to non-U.S. benefit plans about which information is not presented in Note 7 due to immateriality).