Name:	bz_AnnualAppropriationsOfNetAfterTaxProfitsToBeSetAsideAsGeneralReserveFundOrStatutorySurplusFund
Namespace Prefix:	bz_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

This element represents for percentage of appropriation of after tax profit to general reserve fund required percentage minimum.

No definition available.

Name:	bz_AppropriationOfAfterTaxProfitToGeneralReserveFundRequiredPercentageMinimum
Namespace Prefix:	bz_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

This element represents for percentage of appropriation of after tax profit to statutory surplus fund required percentage minimum.

No definition available.

Name:	bz_AppropriationOfAfterTaxProfitToStatutorySurplusFundRequiredPercentageMinimum
Namespace Prefix:	bz_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

This element represents for percentage of total restricted net assets to total consolidated net assets.

No definition available.

Name:	bz_PercentageOfTotalRestrictedNetAssetsToTotalConsolidatedNetAssets
Namespace Prefix:	bz_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

This element represents for entities incorporated in PRC, the ratio of the statutory reserve to the registered capital which triggers the elimination of the requirement to contribute to the statutory reserve.

No definition available.

Name:	bz_RequiredGeneralReserveRegisteredCapitalRatioToDeforceCompulsoryNetProfitAllocationToGeneralReserve
Namespace Prefix:	bz_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

No definition available.

Name:	bz_RequiredStatutorySurplusRegisteredCapitalRatioToDeforceCompulsoryNetProfitAllocationToStatutorySurplus
Namespace Prefix:	bz_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Restricted assets disclosure.

No definition available.

Name:	bz_RestrictedNetAssetsDisclosureLineItems
Namespace Prefix:	bz_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of restricted net assets of consolidated and unconsolidated subsidiaries as of the end of the most recently completed fiscal year.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(3)(ii))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

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

Name:	bz_TypeOfEnterprisesAxis=bz_ForeignInvestedEnterpriseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	bz_ReservesWithinEquityAxis=bz_GeneralReserveFundMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_StatementGeographicalAxis=country_CN
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	bz_TypeOfEnterprisesAxis=bz_DomesticEnterpriseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: