Debt and Financing Arrangements (Details) (USD $) In Millions, unless otherwise specified	Jul. 31, 2013	Apr. 30, 2013
Debt and Financing Arrangements [Abstract]
Total long-term debt	$ 2,017.1	$ 2,017.8
Current portion of long-term debt	150.0	50.0
Total long-term debt, less current portion	1,867.1	1,967.8
[SeniorNotesDuePeriodTwoMember]
Debt Instrument [Line Items]
Company issued Senior Notes	100.0	100.0
[SeniorNotesDuePeriodThreeMember]
Debt Instrument [Line Items]
Company issued Senior Notes	24.0	24.0
[SeniorNotesDuePeriodFourMember]
Debt Instrument [Line Items]
Company issued Senior Notes	394.3	395.0
[SeniorNotesDuePeriodSevenMember]
Debt Instrument [Line Items]
Company issued Senior Notes	748.8	748.8
[SeniorNotesDuePeriodFiveMember]
Debt Instrument [Line Items]
Company issued Senior Notes	350.0	350.0
[SeniorNotesDuePeriodSixMember]
Debt Instrument [Line Items]
Company issued Senior Notes	$ 400.0	$ 400.0

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Carrying amount of long-term debt, net of unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

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