Represents the amount of incentive program expenses which are reported as a contra to net sales.

No definition available.

Name:	krt_IncentiveProgramExpenses
Namespace Prefix:	krt_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of major shareholders who share common ownership.

+ References

No definition available.

+ Details

Name:	krt_NumberOfMajorShareholdersWhoShareCommonOwnershipWithLollicupFranchising
Namespace Prefix:	krt_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of store owned.

+ References

No definition available.

+ Details

Name:	krt_NumberOfStoreOwned
Namespace Prefix:	krt_
Data Type:	xbrli:integerItemType
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_VariableInterestEntityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of maximum exposure to loss from involvement with consolidated variable interest entity (VIE).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 5A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123419778&loc=SL6759159-111685

+ Details

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

- Details

Name:	srt_ConsolidatedEntitiesAxis=krt_LollicupFranchisingLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Summary of Significant Accounting Policies - Lollicup Franchising, LLC (Details) - Lollicup Franchising, LLC		3 Months Ended	6 Months Ended
	Sep. 01, 2020 store shareholder	Jun. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)
Variable Interest Entity [Line Items]
Major shareholders who share common ownership with Lollicup Franchising \| shareholder	2
Store owned \| store	1
Incentive program expenses		26,000	58,000
Maximum exposure to loss				$ 0