XML 62 R51.htm IDEA: XBRL DOCUMENT
v3.22.2

Risk Management and Derivatives: Utilities (Details) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Mar. 31, 2022 | Jun. 30, 2022 USD ($) MMBTU | Dec. 31, 2021 MMBTU
Derivative [Line Items] |  |  |
Credit Risk Derivative Liabilities, at Fair Value | $ |  | $ 0.4 |
Natural Gas, Distribution | Cash Flow Hedging |  |  |
Derivative [Line Items] |  |  |
Derivative, Nonmonetary Notional Amount |  | 2,416,000 |
Natural Gas, Distribution | Natural gas futures purchased |  |  |
Derivative [Line Items] |  |  |
Derivative, Remaining Maturity | 3 months | 9 months |
Natural Gas, Distribution | Natural gas futures purchased | Long |  |  |
Derivative [Line Items] |  |  |
Derivative, Nonmonetary Notional Amount |  | 100,000 | 590,000
Natural Gas, Distribution | Natural gas options purchased, net |  |  |
Derivative [Line Items] |  |  |
Derivative, Remaining Maturity | 3 months | 9 months |
Natural Gas, Distribution | Natural gas options purchased, net | Long |  |  |
Derivative [Line Items] |  |  |
Derivative, Nonmonetary Notional Amount |  | 430,000 | 3,100,000
Natural Gas, Distribution | Natural gas basis swaps purchased |  |  |
Derivative [Line Items] |  |  |
Derivative, Remaining Maturity | 3 months | 0 months |
Natural Gas, Distribution | Natural gas basis swaps purchased | Long |  |  |
Derivative [Line Items] |  |  |
Derivative, Nonmonetary Notional Amount |  | 0 | 870,000
Natural Gas, Distribution | Natural gas over-the-counter swaps, net |  |  |
Derivative [Line Items] |  |  |
Derivative, Remaining Maturity | 34 months | 30 months |
Natural Gas, Distribution | Natural gas over-the-counter swaps, net | Long |  |  |
Derivative [Line Items] |  |  |
Derivative, Nonmonetary Notional Amount |  | 7,090,000 | 4,570,000
Natural Gas, Distribution | Natural gas physical contracts, net |  |  |
Derivative [Line Items] |  |  |
Derivative, Remaining Maturity | 24 months | 18 months |
Natural Gas, Distribution | Natural gas physical contracts, net | Long |  |  |
Derivative [Line Items] |  |  |
Derivative, Nonmonetary Notional Amount |  | 12,166,541 | 16,416,677

X
- Definition The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4H -Subparagraph (d) -URI https://asc.fasb.org/extlink&oid=125515794&loc=SL5624258-113959 + Details
Name: | us-gaap_CollateralAlreadyPostedAggregateFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Nominal number of units used to calculate payment on derivative. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 40 -Section 50 -Paragraph 5 -Subparagraph (f) -URI https://asc.fasb.org/extlink&oid=126731327&loc=d3e90205-114008 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI https://asc.fasb.org/extlink&oid=125515794&loc=SL5580258-113959 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 18 -Subparagraph (c) -URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496189-112644 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1I -Subparagraph (c) -URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495371-112611 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI https://asc.fasb.org/extlink&oid=125515794&loc=SL5579245-113959 + Details
Name: | us-gaap_DerivativeNonmonetaryNotionalAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Period remaining until the derivative contract matures, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_DerivativeRemainingMaturity1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_EnergyAxis=bkh_NaturalGasDistributionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_CashFlowHedgingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_FutureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PositionAxis=us-gaap_LongMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityOptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_BasisSwapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=bkh_FixedforFloatSwapsPurchasedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=bkh_NaturalGasPhysicalPurchasesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |