Condensed Statements of Consolidated Comprehensive Income (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014	Jan. 31, 2013
Condensed Statements of Comprehensive Income [Abstract]
Net income	$ 166.7	$ 154.2	$ 446.7	$ 413.9
Other comprehensive (loss) income:
Foreign currency translation adjustments	(20.0)	1.0	(30.6)	(2.5)
Cash flow hedging derivative activity, net of tax	6.5	2.6	8.1	5.1
Pension and other postretirement benefit plans activity, net of tax	1.7	1.9	4.2	6.1
Available-for-sale securities activity, net of tax	0.5	(0.2)	0.6	0.4
Total Other Comprehensive (Loss) Income	(11.3)	5.3	(17.7)	9.1
Comprehensive Income	$ 155.4	$ 159.5	$ 429.0	$ 423.0