Derivatives and Risk Management Activities - Interest Rate Risk Hedging (Details) - Cash flow hedge $ in Millions	6 Months Ended
Jun. 30, 2023 USD ($) contract
8 forward starting interest rate swaps (30-year), 3.09%
Interest Rate Risk Hedging
Number of interest rate derivatives \| contract	8
Term of derivative contract	30 years
Notional amount of derivatives	$ 200
Average rate locked (percent)	3.09%
4 forward starting interest rate swaps (30-year), 0.74%
Interest Rate Risk Hedging
Number of interest rate derivatives \| contract	4
Term of derivative contract	30 years
Notional amount of derivatives	$ 100
Average rate locked (percent)	0.74%
Interest rate swap terminated
Interest Rate Risk Hedging
Notional amount of derivatives	$ 200

Average fixed interest rate related to the group of interest rate derivatives.

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- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1B

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1A

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- Definition

Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- References

No definition available.

+ Details

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- Definition

Number of interest rate derivative instruments held by the entity at the reporting date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1B

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1A

+ Details

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