Accumulated Other Comprehensive Income Loss (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014		Jan. 31, 2013
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign Currency Translation Adjustment, Beginning Balance			$ 61.5
Reclassification adjustments, Foreign Currency Translation Adjustment			0
Current period (charge) credit, Foreign Currency Translation Adjustment			(30.6)
Income tax expense, Foreign Currency Translation Adjustment			0
Foreign Currency Translation Adjustment, Ending Balance	30.9		30.9
Pension and Other Postretirement Liabilities, Beginning Balance			(131.4)
Reclassification adjustments, Pension and Other Postretirement Liabilities			8.9	[1]
Current period (charge) credit, Pension and Other Postretirement Liabilities			(2.2)
Income tax expense, Pension and Other Postretirement Liabilities			(2.5)
Pension and Other Postretirement Liabilities, Ending Balance	(127.2)		(127.2)
Unrealized Gain (Loss) on Available-for-Sale Securities, Beginning Balance			4.5
Reclassification adjustments, Unrealized Gain (Loss) on Available-for-Sale Securities			0
Current period (charge) credit, Unrealized Gain (Loss) on Available-for-Sale Securities			0.9
Income tax expense, Unrealized Gain (Loss) on Available-for-Sale Securities			(0.3)
Unrealized Gain (Loss) on Available-for-Sale Securities, Ending Balance	5.1		5.1
Unrealized (Loss) Gain on Cash Flow Hedging Derivatives, Beginning Balance			(11.2)
Reclassification adjustments, Unrealized (Loss) Gain on Cash Flow Hedging Derivatives			18.8	[2]
Current period (charge) credit, Unrealized (Loss) Gain on Cash Flow Hedging Derivative			(6.1)
Income tax expense, Unrealized (Loss) Gain on Cash Flow Hedging Derivatives			(4.6)
Unrealized (Loss) Gain on Cash Flow Hedging Derivatives, Ending Balance	(3.1)		(3.1)
Accumulated Other Comprehensive (Loss) Income, Beginning Balance			(76.6)
Reclassification adjustments, Accumulated Other Comprehensive (Loss) Income			27.7
Current period (charge) credit, Accumulated Other Comprehensive (Loss) Income			(38.0)
Income tax expense, Accumulated Other Comprehensive (Loss) Income			(7.4)
Accumulated Other Comprehensive (Loss) Income, Ending Balance	(94.3)		(94.3)
Commodity contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Losses reclassified from other comprehensive income to interest expense	5.7	12.0	18.4		31.0
Interest rate contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Losses reclassified from other comprehensive income to interest expense	$ 0.1	$ 0.1	$ 0.4		$ 0.4

[1] Amortization of net losses was reclassified from accumulated other comprehensive loss to selling, distribution, and administrative expenses.

[2] Of the total losses reclassified from accumulated other comprehensive loss, $18.4 was reclassified to cost of products sold related to commodity derivatives and $0.4 was reclassified to interest expense related to the interest rate swap.