XML 86 R64.htm IDEA: XBRL DOCUMENT
v3.20.4

Accounting Policies - Derivatives (Details 10) - MMBTU | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019
Commodity Contract [Member] | Not Designated as Hedging Instrument, Economic Hedge [Member] |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |
Derivative, Nonmonetary Notional Amount, Energy Measure | 1,400,000 | 535,000

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

X
- Definition Nominal energy measure used to calculate payments on a derivative instrument. + References No definition available. + Details
Name: | us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure
Namespace Prefix: | us-gaap_
Data Type: | num:energyItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | us-gaap_HedgingDesignationAxis=us-gaap_NotDesignatedAsHedgingInstrumentEconomicHedgeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |