Debt Instrument, Periodic Payment, Percent

No definition available.

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

- Definition

Represents the maximum increase in the available borrowing capacity of the credit facility subject to certain limitations and satisfaction of certain conditions, including compliance with certain financial covenants.

+ References

No definition available.

+ Details

Name:	knl_LineOfCreditFacilityBorrowingCapacityAvailableIncrease
Namespace Prefix:	knl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line Of Credit Facility, Borrowing Capacity Available Increase, Percent Of EBITDA

+ References

No definition available.

+ Details

Name:	knl_LineOfCreditFacilityBorrowingCapacityAvailableIncreasePercentOfEBITDA
Namespace Prefix:	knl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of amortization expense attributable to debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
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-Name Accounting Standards Codification
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
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-Section 45
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+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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 issuance costs related to line of credit arrangements. 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 835
-SubTopic 30
-Section S45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=68176171&loc=SL68176184-208336

+ Details

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

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
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

Weighted average interest rate of long-term debt outstanding calculated at point in time.

+ References

No definition available.

+ Details

Name:	us-gaap_LongtermDebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

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+ Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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Balance Type:
Period Type:

- Details

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Period Type:

- Details

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Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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Balance Type:
Period Type:

- Details

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INDEBTEDNESS - Narrative (Details)		12 Months Ended
INDEBTEDNESS - Narrative (Details)	Aug. 26, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 23, 2018 USD ($)	Jan. 23, 2018 EUR (€)
Debt Instrument [Line Items]
Borrowings under revolving credit facility		$ 417,500,000	$ 490,500,000	$ 310,000,000.0
Quarterly payments, percent of annum		5.00%
Amortization expense related to the deferred financing fees		$ 1,000,000.0	1,100,000	700,000
Loss on extinguishment of debt		400,000	1,400,000	$ 0
Credit Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Commitments		$ 400,000,000.0	$ 400,000,000.0
Amended Credit Agreement
Debt Instrument [Line Items]
Commitments					$ 750,000,000.0
Borrowing capacity available increase					$ 250,000,000.0
Available increase, percent of EBITDA					90.00%	90.00%
Amended Credit Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Commitments					$ 400,000,000.0
Amended Credit Agreement \| U.S. term loan
Debt Instrument [Line Items]
Debt face amount					$ 250,000,000.0
Amended Credit Agreement \| Multi-currency term loans
Debt Instrument [Line Items]
Debt face amount \| €						€ 81,700,000
Credit Agreement \| Federal Funds Rate
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	0.50%
Credit Agreement \| Eurocurrency Rate
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.00%
Credit Agreement \| Revolving Credit Facility \| Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		5.25%	6.25%
Borrowings under revolving credit facility		$ 10,000,000.0	$ 2,500,000
Credit Agreement \| Revolving Credit Facility \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		3.27%	4.25%
Borrowings under revolving credit facility		$ 128,500,000	$ 132,000,000.0
Credit Agreement \| Letter of Credit
Debt Instrument [Line Items]
Weighted average interest rate		1.50%	1.75%
Amended Credit Agreement
Debt Instrument [Line Items]
Debt issuance costs, line of credit	$ 2,000,000.0
Loss on extinguishment of debt	$ 400,000
Amended Credit Agreement \| U.S. term loan
Debt Instrument [Line Items]
Interest rate incurred		3.30%	4.27%
Amended Credit Agreement \| Multi-currency term loans
Debt Instrument [Line Items]
Interest rate incurred		1.50%	1.75%
Minimum
Debt Instrument [Line Items]
Commitment fee rate		0.225%
Maximum
Debt Instrument [Line Items]
Commitment fee rate		0.25%