Derivative Financial Instruments (Details Textual) - USD ($) $ in Millions	9 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Apr. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	$ 1,274		$ 1,212
Derivative Financial Instruments (Textual) [Abstract]
Foreign Currency Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months	$ 45
Maximum term of outstanding derivative contracts	36 months
Aggregate fair value of derivatives with creditworthiness requirements that were in a net liability position	$ 0		$ 18
Treasury Lock [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	$ 8	$ 0