Debt Instrument Amortization of Principal Percentage Year Five

No definition available.

Name:	kfy_DebtInstrumentAmortizationOfPrincipalPercentageYearFive
Namespace Prefix:	kfy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument Amortization of Principal Percentage Year Four

+ References

No definition available.

+ Details

Name:	kfy_DebtInstrumentAmortizationOfPrincipalPercentageYearFour
Namespace Prefix:	kfy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument Amortization Of Principal Percentage Year One

+ References

No definition available.

+ Details

Name:	kfy_DebtInstrumentAmortizationOfPrincipalPercentageYearOne
Namespace Prefix:	kfy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument Amortization Of Principal Percentage Year Three

+ References

No definition available.

+ Details

Name:	kfy_DebtInstrumentAmortizationOfPrincipalPercentageYearThree
Namespace Prefix:	kfy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument Amortization Of Principal Percentage Year Two

+ References

No definition available.

+ Details

Name:	kfy_DebtInstrumentAmortizationOfPrincipalPercentageYearTwo
Namespace Prefix:	kfy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The minimum amount of Domestic Liquidity must maintain in order to be in compliance with the debt covenant.

+ References

No definition available.

+ Details

Name:	kfy_LineOfCreditFacilityCovenantAmount
Namespace Prefix:	kfy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Policy Loans Payable

+ References

No definition available.

+ Details

Name:	kfy_PolicyLoansPayable
Namespace Prefix:	kfy_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Pro forma leverage ratio.

+ References

No definition available.

+ Details

Name:	kfy_ProFormaLeverageRatio
Namespace Prefix:	kfy_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

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

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

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The average effective interest rate during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

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

Name:	us-gaap_DebtInstrumentInterestRateDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
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

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DeferredFinanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the credit facility first became available, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInitiationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- 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

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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

- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

+ Details

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

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_StandbyLettersOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=kfy_CSVOfColiContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=kfy_OtherFinancialInstitutionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=kfy_CreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=kfy_TermFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Long-Term Debt - Additional Information (Detail)		12 Months Ended
Long-Term Debt - Additional Information (Detail)	Jun. 15, 2016 USD ($)	Apr. 30, 2018 USD ($)	Apr. 30, 2017 USD ($)	Apr. 30, 2016 USD ($)
Debt Instrument [Line Items]
Principal payment on term loan facility		$ 20,625,000	$ 155,469,000	$ 10,000,000
Long-term debt		238,906,000
Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility borrowings		0	0
Line of credit facility, remaining borrowing capacity		122,100,000	122,000,000
Standby Letters of Credit
Debt Instrument [Line Items]
Long-term debt arrangement		2,900,000	3,000,000
CSV of COLI Contracts
Debt Instrument [Line Items]
Outstanding policy loans		$ 66,700,000	67,200,000
CSV of COLI Contracts \| Minimum
Debt Instrument [Line Items]
Average interest rate		4.76%
CSV of COLI Contracts \| Maximum
Debt Instrument [Line Items]
Average interest rate		8.00%
Other Financial Institutions \| Standby Letters of Credit
Debt Instrument [Line Items]
Long-term debt arrangement		$ 7,400,000	8,100,000
Credit Agreement
Debt Instrument [Line Items]
Credit agreement initiation date	Jun. 15, 2016
Line of credit facility, maximum borrowing capacity	$ 400,000,000
Line of credit facility borrowings	275,000,000
Principal payment on term loan facility	140,000,000
Unamortized debt issuance costs		$ 2,700,000	3,500,000
Credit Agreement \| Minimum
Debt Instrument [Line Items]
Pro forma domestic liquidity	$ 50,000,000
Credit Agreement \| Maximum
Debt Instrument [Line Items]
Pro forma leverage ratio	2.50
Credit Agreement \| London Interbank Offered Rate (LIBOR) \| Minimum
Debt Instrument [Line Items]
Applicable margin on variable interest rate		1.25%
Credit Agreement \| London Interbank Offered Rate (LIBOR) \| Maximum
Debt Instrument [Line Items]
Applicable margin on variable interest rate		2.00%
Credit Agreement \| Base Rate Loans \| Minimum
Debt Instrument [Line Items]
Applicable margin on variable interest rate		0.25%
Credit Agreement \| Base Rate Loans \| Maximum
Debt Instrument [Line Items]
Applicable margin on variable interest rate		1.00%
Credit Agreement \| Term Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 275,000,000
Term loan amortization percentage year one	7.50%
Term loan amortization percentage year two	7.50%
Term loan amortization percentage year three	10.00%
Term loan amortization percentage year four	10.00%
Term loan amortization percentage year five	10.00%
Principal payment on term loan facility		$ 20,600,000	$ 15,500,000
Average interest rate		2.60%	2.23%
Long-term debt		$ 238,900,000	$ 259,500,000
Line of credit facility, maturity date		Jun. 15, 2021
Credit Agreement \| Term Facility \| Minimum
Debt Instrument [Line Items]
Quarterly fee on average daily unused amount of Credit Facilities		0.20%
Credit Agreement \| Term Facility \| Maximum
Debt Instrument [Line Items]
Quarterly fee on average daily unused amount of Credit Facilities		0.35%
Credit Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 125,000,000
Line of credit facility, maturity date		Jun. 15, 2021