Long-term Debt and Finance Lease Obligations, Lines of Credit and Fair Value Disclosure - Narrative (Details) - USD ($)	3 Months Ended
Jul. 31, 2022	Apr. 30, 2022
Debt Instrument
Fair value of long-term debt	$ 1,509,000,000	$ 1,508,000,000
Finance lease obligations	73,890,000	74,234,000
Unsecured Revolving Credit Facility Due January 2024 \| Revolving Credit Facility
Debt Instrument
Maximum borrowing capacity	450,000,000
Fair value of amount outstanding	$ 0	0
Unsecured Revolving Credit Facility Due January 2024 \| Revolving Credit Facility \| Federal Funds
Debt Instrument
Effective percentage	0.50%
Unsecured Revolving Credit Facility Due January 2024 \| Revolving Credit Facility \| Alternate Base Rate
Debt Instrument
Effective percentage	1.00%
Unsecured Revolving Credit Facility Due January 2024 \| Minimum \| Revolving Credit Facility
Debt Instrument
Facility fee percentage	0.20%
Unsecured Revolving Credit Facility Due January 2024 \| Minimum \| Revolving Credit Facility \| LIBOR
Debt Instrument
Effective percentage	0.50%
Basis spread on variable rate	1.05%
Unsecured Revolving Credit Facility Due January 2024 \| Minimum \| Revolving Credit Facility \| Alternate Base Rate
Debt Instrument
Basis spread on variable rate	0.05%
Unsecured Revolving Credit Facility Due January 2024 \| Maximum \| Revolving Credit Facility
Debt Instrument
Facility fee percentage	0.40%
Unsecured Revolving Credit Facility Due January 2024 \| Maximum \| Revolving Credit Facility \| LIBOR
Debt Instrument
Basis spread on variable rate	1.85%
Unsecured Revolving Credit Facility Due January 2024 \| Maximum \| Revolving Credit Facility \| Alternate Base Rate
Debt Instrument
Basis spread on variable rate	0.85%
Unsecured Revolving Line of Credit \| Line of Credit
Debt Instrument
Maximum borrowing capacity	$ 25,000,000
Fair value of amount outstanding	0	$ 0
Unsecured Revolving Line of Credit \| Letter of Credit
Debt Instrument
Maximum borrowing capacity	$ 5,924,000

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6036836-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Present value of lessee's discounted obligation for lease payments from finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918701-209980

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Fair value of the amount outstanding under the credit facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=123594938&loc=d3e13433-108611

+ Details

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Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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