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Regulatory Matters: Winter Storm Uri (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Public Utilities, General Disclosures [Line Items]
Regulatory assets	$ 723,344	$ 796,599
Winter Storm Uri Incremental Costs in a Separately Tracked Mechanism
Public Utilities, General Disclosures [Line Items]
Regulatory assets	438,675	509,025
Winter Storm Uri
Public Utilities, General Disclosures [Line Items]
Amount Recovered Through Regulatory Mechanism	$ 73,000
Winter Storm Uri | Winter Storm Uri Incremental Costs in a Separately Tracked Mechanism
Public Utilities, General Disclosures [Line Items]
Regulatory assets		$ 546,000
Regulatory Asset, Amortization Period	3 years 1 month 6 days	3 years 6 months
Winter Storm Uri | Carrrying Costs
Public Utilities, General Disclosures [Line Items]
Regulatory assets	$ 2,300		$ 0

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Amount Recovered Through Regulatory Mechanism

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Amortization period for the recovery of regulatory asset, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 340
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382

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