Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Oct. 31, 2011	Oct. 31, 2010	Oct. 31, 2011	Oct. 31, 2010
Summarized net income for the other items included in the determination of comprehensive income:
Net income	$ 157.6	$ 154.0	$ 275.6	$ 265.4
Other comprehensive income (loss), net of tax:
Postretirement benefits adjustment	3.3	3.1	6.6	5.7
Foreign currency translation adjustment	(34.3)	14.5	(43.6)	5.7
Net (loss) gain on cash flow hedges	4.6	(6.4)	8.6	(8.8)
Total Other comprehensive income (loss)	(26.4)	11.2	(28.4)	2.6
Comprehensive income	$ 131.2	$ 165.2	$ 247.2	$ 268.0

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the reporting entity. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, but excludes any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

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-Publisher FASB

-Name Accounting Standards Codification

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-Name Accounting Standards Codification

-Glossary Net Income

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-Glossary Other Comprehensive Income

-URI http://asc.fasb.org/extlink&oid=6519514

+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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+ Details

- Definition

The increase (decrease) to accumulated comprehensive income during the period related to benefit plans, after tax, attributable to the parent entity.

+ References

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+ Details

- Definition

Net of tax effect change in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges, that is attributable to the parent entity. The change includes an entity's share of an equity investee's increase (decrease) in deferred hedging gains or losses.

+ References

+ Details

- Definition

Adjustment that results from the process of translating subsidiary financial statements and foreign equity investments into functional currency of the reporting entity, net of tax, attributable to the parent entity.

+ References

+ Details

- Definition

This element represents Other Comprehensive Income or Loss, Net of Tax, for the period attributable to the parent entity. Includes deferred gains or losses on qualifying hedges, unrealized holding gains or losses on available-for-sale securities, minimum pension liability, and cumulative translation adjustment.

+ References

+ Details