Amended Net Debt to EBITDA Ratio, allowable adjustment for cash restructuring charges, amount

No definition available.

Name:	kmt_AmendedNetDebtToEBITDARatioAllowableAdjustmentForCashRestructuringChargesAmount
Namespace Prefix:	kmt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amended Net Debt to EBITDA Ratio, Maximum

+ References

No definition available.

+ Details

Name:	kmt_AmendedNetDebtToEBITDARatioMaximum
Namespace Prefix:	kmt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Consolidated Interest Coverage Ratio, Minimum

+ References

No definition available.

+ Details

Name:	kmt_ConsolidatedInterestCoverageRatioMinimum
Namespace Prefix:	kmt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Long term debt and capital leases.

+ References

No definition available.

+ Details

Name:	kmt_LongTermDebtAndCapitalLeasesAdditionalTextualAbstract
Namespace Prefix:	kmt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Long term debt and capital leases.

+ References

No definition available.

+ Details

Name:	kmt_LongTermDebtAndCapitalLeasesTextualAbstract
Namespace Prefix:	kmt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Long-Term Debt, Maturities, Repayments Of Principal In Rolling After Year Ten

+ References

No definition available.

+ Details

Name:	kmt_LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingAfterYearTen
Namespace Prefix:	kmt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Net Debt to EBITDA Ratio, Maximum

+ References

No definition available.

+ Details

Name:	kmt_NetDebttoEBITDARatioMaximum
Namespace Prefix:	kmt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Net Debt to EBITDA Ratio, domestic cash allowed to net debt, amount, minimum

+ References

No definition available.

+ Details

Name:	kmt_NetDebttoEBITDARatiodomesticcashallowedtonetdebtamountminimum
Namespace Prefix:	kmt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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

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 discount.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28541-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- 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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28555-108399

+ Details

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

- 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=121572278&loc=d3e13433-108611

+ Details

Name:	us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

+ 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

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870

Reference 2: 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(a)(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 3: 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=120398452&loc=d3e534808-122878

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))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

Amount of long-term debt and lease obligation, classified as noncurrent.

+ References

+ Details

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

- Definition

Amount of long-term debt and lease obligation, including portion classified as current.

+ References

No definition available.

+ Details

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

- 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

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

- Definition

Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04.(a))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24072-122690

+ Details

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

- Definition

Amount of cash outflow for cost from early extinguishment and prepayment of debt. Includes, but is not limited to, third-party cost, premium paid, and other fee paid to lender directly for debt extinguishment or debt prepayment. Excludes accrued interest.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

+ Details

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

- Definition

The cash inflow provided by derivative instruments during the period, which are classified as financing activities, excluding those designated as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3505-108585

+ Details

Name:	us-gaap_ProceedsFromDerivativeInstrumentFinancingActivities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow from a borrowing with the highest claim on the assets of the entity in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle, if longer).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_LongtermDebtTypeAxis=kmt_ThreePointEightSevenFivePercentSeniorUnsecuredNotesDueInTwoThousandAndTwentyTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=kmt_FourPointSixTwoFivePercentSeniorUnsecuredNotesDueInTwoThousandAndTwentyEightMemberMemberMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=kmt_TwoPointEightPercentSeniorUnsecuredNotesDueInTwoThousandAndThirtyOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

Long-Term Debt (Details) - USD ($)				9 Months Ended
Long-Term Debt (Details) - USD ($)	Feb. 23, 2021	Jun. 07, 2018	Feb. 14, 2012	Mar. 31, 2021	Jun. 30, 2020
Long-Term Debt (Additional Textual) [Abstract]
Fixed rate at fair market value				$ 628,400,000	$ 630,200,000
Debt Instrument [Line Items]
Long-term Debt and Lease Obligation, Including Current Maturities				595,748,000	598,204,000
Debt Issuance Costs, Net				(4,076,000)	(4,121,000)
Long-term Debt and Lease Obligation				591,672,000	594,083,000
Long-term Debt, Maturities, Repayments of Principal in Rolling after Year Five				300,000,000
Long-Term Debt, Maturities, Repayments Of Principal In Rolling After Year Ten				300,000,000
Settlement of interest rate swap agreement (Note 5)				10,198,000
Make-whole premium on early extinguishment of debt (Note 10)				(9,639,000)
ThreePointEightSevenFivePercentSeniorUnsecuredNotesDueInTwoThousandAndTwentyTwo [Member]
Long-Term Debt (Additional Textual) [Abstract]
Proceeds from Issuance of Senior Long-term Debt			$ 300,000,000.0
Debt Instrument, Interest Rate, Stated Percentage			3.875%
Debt Instrument [Line Items]
Long-term Debt					299,940,000
Debt Instrument, Interest Rate, Stated Percentage			3.875%
Debt Instrument, Unamortized Discount					100,000
Four Point Six Two Five Percent Senior Unsecured Notes Due In Two Thousand And Twenty Eight Member Member
Long-Term Debt (Additional Textual) [Abstract]
Proceeds from Issuance of Senior Long-term Debt		$ 300,000,000.0
Debt Instrument, Interest Rate, Stated Percentage		4.625%
Debt Instrument [Line Items]
Long-term Debt				298,428,000	298,264,000
Debt Instrument, Interest Rate, Stated Percentage		4.625%
Debt Instrument, Unamortized Discount				1,600,000	1,700,000
Two Point Eight Percent Senior Unsecured Notes Due In Two Thousand And Thirty One
Long-Term Debt (Additional Textual) [Abstract]
Proceeds from Issuance of Senior Long-term Debt	$ 300,000,000.0
Debt Instrument, Interest Rate, Stated Percentage	2.80%
Debt Instrument [Line Items]
Long-term Debt				297,320,000
Debt Instrument, Interest Rate, Stated Percentage	2.80%
Debt Instrument, Unamortized Discount				2,700,000
2018 Credit Agreement [Member]
Long-Term Debt (Textual) [Abstract]
Line of Credit Facility, Remaining Borrowing Capacity				670,000,000.0
Borrowing outstanding under 2018 Credit Agreement				10,000,000.0	$ 500,000,000.0
Line of Credit Facility, Maximum Borrowing Capacity		$ 700,000,000.0
Line of Credit [Member]
Long-Term Debt (Textual) [Abstract]
Amended Net Debt to EBITDA Ratio, allowable adjustment for cash restructuring charges, amount				120,000,000
Amended Net Debt to EBITDA Ratio, Maximum				4.25
Consolidated Interest Coverage Ratio, Minimum				3.5
Net Debt to EBITDA Ratio, Maximum				3.5
Net Debt to EBITDA Ratio, domestic cash allowed to net debt, amount, minimum				$ 25,000,000