XML 81 R69.htm IDEA: XBRL DOCUMENT
v3.20.2

Investments (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |  |
--- | --- | --- | --- | ---
Sep. 30, 2020 | Mar. 31, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019 | Dec. 31, 2019 | Feb. 28, 2018
Assets used to Acquire Other Investments |  |  |  |  |  |  | $ 28,000
Impairment of investment | $ 0 | $ 6,900 | $ 19,741 | $ 6,859 | $ 19,741 |  |
Investments | 15,659 |  |  | 15,659 |  | $ 21,929 |
Investment in privately held oil and gas company |  |  |  |  |  |  |
Investments | 1,500 |  |  | 1,500 |  | 8,359 |
Cash surrender value of life insurance contracts |  |  |  |  |  |  |
Investments | 13,467 |  |  | 13,467 |  | 13,056 |
Other investments |  |  |  |  |  |  |
Investments | $ 692 |  |  | $ 692 |  | $ 514 |
Valuation, Income Approach |  |  |  |  |  |  |
Discount Rate Used in Valuation of Fair Value of Oil and Gas Reserve Quantities |  |  | 10.00% |  | 10.00% |  |

X
- Definition Assets Used to Acquire Other Investments + References No definition available. + Details
Name: | bkh_AssetsUsedtoAcquireOtherInvestments
Namespace Prefix: | bkh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Discount Rate Used in Valuation of Fair Value of Oil and Gas Reserve Quantities + References No definition available. + Details
Name: | bkh_DiscountRateUsedinValuationofFairValueofOilandGasReserveQuantities
Namespace Prefix: | bkh_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The total amount of investments that are intended to be held for an extended period of time (longer than one operating cycle). + 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 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LongTermInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The charge against earnings resulting from the write down of long lived assets other than goodwill due to the difference between the carrying value and lower fair value. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2921-110230 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 + Details
Name: | us-gaap_OtherAssetImpairmentCharges
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_CashSurrenderValueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_InvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=us-gaap_IncomeApproachValuationTechniqueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |