XML 111 R100.htm IDEA: XBRL DOCUMENT v3.25.0.1

Income Taxes (Additional Information) (Details) - USD ($)	1 Months Ended
	Jan. 31, 2025	Jun. 30, 2024
Income Tax Disclosure [Line Items]
Transfers of production tax credits to third party		$ 16,900,000
Subsequent Event
Income Tax Disclosure [Line Items]
Transfers of production tax credits to third party	$ 17

X

- Definition

Income tax disclosure.

+ References

No definition available.

+ Details

Name:	bkh_IncomeTaxDisclosureLineItems
Namespace Prefix:	bkh_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Transfers of production tax credits to third party.

+ References

No definition available.

+ Details

Name:	bkh_TransfersOfProductionTaxCreditsToThirdParty
Namespace Prefix:	bkh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: