XML 100 R84.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Financing: Shareholder Dividend Reinvestment and Stock Purchase Plan (Details) | Dec. 31, 2021 shares
--- | ---
Class of Stock [Line Items] |
Unissued Shares Available | 116,306
Dividend Reinvestment Plan |
Class of Stock [Line Items] |
Percent of recent average market price | 100.00%

X
- Definition Common stock purchase percentage of recent average market price + References No definition available. + Details
Name: | bkh_CommonStockPurchasePercentageOfRecentAverageMarketPrice
Namespace Prefix: | bkh_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- 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_ClassOfStockLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Aggregate number of common shares reserved for future issuance. + 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 -Subparagraph (SX 210.5-02.29) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_PlanNameAxis=bkh_DividendReinvestmentandStockPurchasePlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |