Letters of credit as additional security for lease guarantees.

No definition available.

Name:	kld_LettersOfCreditAsAdditionalSecurityForLeaseGuarantees
Namespace Prefix:	kld_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Net operating loss carrybacks, Period

+ References

No definition available.

+ Details

Name:	kld_NetOperatingLossCarrybacksPeriod
Namespace Prefix:	kld_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of letters of credit.

+ References

No definition available.

+ Details

Name:	kld_NumberOfLettersOfCredit
Namespace Prefix:	kld_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of taxable income offset by net operating loss carryforwards and carrybacks.

+ References

No definition available.

+ Details

Name:	kld_PercentageOfTaxableIncomeOffsetByNetOperatingLossCarryforwardsAndCarrybacks
Namespace Prefix:	kld_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based compensation arrangement by share-based payment award, salary exchange program for award, percentage.

+ References

No definition available.

+ Details

Name:	kld_ShareBasedCompensationArrangementByShareBasedPaymentAwardSalaryExchangeProgramForAwardPercentage
Namespace Prefix:	kld_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Tax-deductible interest, base percentage.

+ References

No definition available.

+ Details

Name:	kld_TaxDeductibleInterestBasePercentage
Namespace Prefix:	kld_
Data Type:	dtr-types: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_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Gross number of share options (or share units) granted during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PlanNameAxis=kld_SalaryExchangeProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies - Additional Information (Detail) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2021 USD ($) LetterofCredit	Dec. 31, 2020 shares	Dec. 31, 2019
Loss Contingencies [Line Items]
Number of letters of credit \| LetterofCredit	2
Letters of credit as additional security for lease guarantees \| $	$ 0.6
Percentage of taxable income offset by NOL carryforwards and carrybacks	100.00%
Net operating loss carrybacks, period	5 years
Tax-deductible interest, base percentage		50.00%	30.00%
Salary Exchange Program [Member] \| Minimum [Member]
Loss Contingencies [Line Items]
Percentage of salary exchange program for award		2.00%
Salary Exchange Program [Member] \| Maximum [Member]
Loss Contingencies [Line Items]
Percentage of salary exchange program for award		20.00%
Salary Exchange Program [Member] \| Employee Stock Options [Member]
Loss Contingencies [Line Items]
Options granted		417,673
Salary Exchange Program [Member] \| Restricted Stock Units [Member]
Loss Contingencies [Line Items]
Granted		211,207