Financial Instrument [Line Items]

No definition available.

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- Definition

Interest expense recognized on termination of interest rate swap.

+ References

No definition available.

+ Details

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Namespace Prefix:	kfy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Marketable securities remaining maturity.

+ References

No definition available.

+ Details

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- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4CC
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109998890-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

+ Details

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

- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

The cash inflow associated with the aggregate amount received by the entity through sale or maturity of marketable securities (held-to-maturity or available-for-sale) during the period.

+ References

No definition available.

+ Details

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

- Details

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- Details

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- Details

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- Details

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- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeForwardMember
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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Dec. 16, 2019	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019	Apr. 30, 2019	Mar. 31, 2017
Designated as Hedge Instrument \| Interest Rate Swap \| Cash Flow Hedge
Financial Instrument [Line Items]
Derivative notional amount							$ 129,800
Interest rate		1.919%		1.919%
Interest expense recognized on termination of interest rate swap	$ 500
Not Designated as Hedge Instrument \| Foreign Exchange Forward Contracts
Financial Instrument [Line Items]
Foreign currency gains		$ 500	$ 700	$ 1,000	$ 600
Not Designated as Hedge Instrument \| Foreign Exchange Forward Contracts \| Income Taxes And Other Receivables \| Derivatives Purchased
Financial Instrument [Line Items]
Derivative notional amount		78,400		78,400		$ 51,400
Not Designated as Hedge Instrument \| Foreign Exchange Forward Contracts \| Income Taxes And Other Receivables \| Derivatives Sold
Financial Instrument [Line Items]
Derivative notional amount		58,500		58,500		$ 40,000
ECAP
Financial Instrument [Line Items]
Sale/maturities of available-for-sale marketable securities		$ 0		$ 0
Available-for-sale Marketable Securities \| Minimum
Financial Instrument [Line Items]
Marketable securities remaining maturity				3 months
Available-for-sale Marketable Securities \| Maximum
Financial Instrument [Line Items]
Marketable securities remaining maturity				11 months