Debt and Available Credit Facilities (Details) - USD ($) $ in Millions	12 Months Ended
Apr. 30, 2019	Apr. 30, 2018
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Outstanding borrowings under revolving credit facilities	$ 478.8	$ 360.0
Amount of financing available under credit facilities	1,100.0
Unused lines of credit	$ 600.0
Weighted average interest rate on total debt outstanding during the period	2.69%	2.44%
Weighted average interest rate on total debt at period end	2.88%	2.58%
Syndicate Bank Group led by Bank of America [Member] \| Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Amount of financing available under credit facilities	$ 1,100.0
Line of credit facility, due date	Mar. 01, 2021
Term of credit facility	5 years
Optional credit limit increase available on request	$ 350.0
Minimum increments in which optional credit limit increase may be requested	$ 50.0
Syndicate Bank Group led by Bank of America [Member] \| Revolving Credit Facility [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Line of credit facility fee percentage	0.15%
Syndicate Bank Group led by Bank of America [Member] \| Revolving Credit Facility [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Line of credit facility fee percentage	0.25%
Syndicate Bank Group led by Bank of America [Member] \| Revolving Credit Facility [Member] \| LIBOR [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Applicable margin	0.98%
Syndicate Bank Group led by Bank of America [Member] \| Revolving Credit Facility [Member] \| LIBOR [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Applicable margin	1.50%
Syndicate Bank Group led by Bank of America [Member] \| Revolving Credit Facility [Member] \| Base Rate [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Applicable margin	0.00%
Syndicate Bank Group led by Bank of America [Member] \| Revolving Credit Facility [Member] \| Base Rate [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Applicable margin	0.45%
Syndicate Bank Group led by Bank of America [Member] \| Revolving Credit Facility [Member] \| Federal Funds Effective Rate [Member]
Line of Credit Facility [Line Items]
Margin rate over reference rate used in determining base rate	0.50%
Syndicate Bank Group led by Bank of America [Member] \| Revolving Credit Facility [Member] \| Eurocurrency Rate [Member]
Line of Credit Facility [Line Items]
Margin rate over reference rate used in determining base rate	1.00%
Other Credit Facilities [Member] \| Line of Credit [Member]
Line of Credit Facility [Line Items]
Outstanding borrowings under revolving credit facilities	$ 0.0	$ 0.0
Amount of financing available under credit facilities	$ 2.7

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

No definition available.

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Namespace Prefix:	jwa_
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Period Type:	duration

- Definition

Margin rate over reference rate used to calculate the lenders base rate.

+ References

No definition available.

+ Details

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- Definition

The minimum incremental amount by which the entity may request an optional increase to the maximum borrowing capacity under the revolving credit facility.

+ References

No definition available.

+ Details

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Namespace Prefix:	jwa_
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Balance Type:	debit
Period Type:	instant

- Definition

The total amount by which the entity may request an optional increase to the maximum borrowing capacity under the revolving credit facility. This may consist of one request or several requests in minimum increments as specified under the revolving credit agreement.

+ References

No definition available.

+ Details

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Namespace Prefix:	jwa_
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Balance Type:	credit
Period Type:	instant

- Definition

The average effective interest rate during the reporting period.

+ References

Reference 1: 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=114775744&loc=d3e28551-108399

Reference 2: 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=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ 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(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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Namespace Prefix:	us-gaap_
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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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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- 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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- 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

+ Details

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- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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