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Basis of Presentation (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Jan. 31, 2019	Apr. 30, 2019
Reclassification for Costs to Fulfill Contract and Product Development Spending [Member]
Prior Period Adjustments [Abstract]
Prior period reclassification adjustment	$ 4.5
Reclassification for Amortization Expense Related to Costs to Fulfill Contract [Member]
Prior Period Adjustments [Abstract]
Prior period reclassification adjustment	$ 1.9
Correction in Presentation of Certain Consideration Received for Services Not Yet Performed [Member] | Revision of Prior Period, Error Correction, Adjustment [Member]
Prior Period Adjustments [Abstract]
Increase in accounts receivable, net		$ 11.8
Increase in contract liabilities		$ 11.8

X

- Definition

Increase (Decrease) in amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Amount of increase (decrease) in obligation to transfer good or service to customer for which consideration has been received or is receivable.

+ References

No definition available.

+ Details

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Namespace Prefix:	jwa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- References

No definition available.

+ Details

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

X

- Definition

The amount of a reclassification adjustment made to prior period financial statement amounts.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

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Namespace Prefix:
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X

- Details

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Namespace Prefix:
Data Type:	na
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X

- Details

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Data Type:	na
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Period Type:

X

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: