Pension and Other Postretirement Benefits (Textual) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Apr. 30, 2013
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans in 2014	$ 34
Estimated amount of prior service cost that will be amortized from accumulated other comprehensive loss into Pension expense in 2013	1
Estimated amount of net actuarial loss that will be amortized from accumulated other comprehensive loss into pension expense in 2013	31
Medical and Life Insurance Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans in 2014	3
Project health care cost trend rates to decline gradually to, by 2021 and thereafter	5.00%
1% increase in assumed health care cost trend rates would have increased the accumulated postretirement benefit obligation	11
1% increase in assumed health care cost trend rates would have increased the aggregate service and interest costs	1
1% decrease in assumed health care cost trend rates would have decreased the accumulated postretirement benefit obligation	9
1% decrease in assumed health care cost trend rates would have decreased the aggregate service and interest costs	$ 1

The amounts in accumulated other comprehensive income related to gains and losses that are not recognized immediately and are expected to be recognized as components of net periodic benefit cost over the next fiscal year that follows the most recent annual statement of financial position presented.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (s)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 158

-Paragraph 7

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph s

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

The amounts in accumulated other comprehensive income related to prior service cost or credit expected to be recognized as components of net periodic benefit cost over the next fiscal year that follows the most recent annual statement of financial position presented.

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- Definition

Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

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Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

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- Definition

The effect of a one-percentage-point increase in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

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The effect of a one-percentage-point increase in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

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- Definition

The employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions.

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- Definition

The ultimate trend rate for health care costs.

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