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Regulatory Matters: Rate Review (Details) $ in Thousands	Mar. 01, 2021 USD ($)	Jan. 26, 2021 USD ($) mi	Sep. 11, 2020	Jan. 06, 2021 mi	Dec. 30, 2020 USD ($)
Colorado Public Utilities Commission (CPUC) | Colorado Electric
Public Utilities, General Disclosures [Line Items]
Settlement of plan to provide TCJA-related customer billing credits to its customers					$ 9,300
Nebraska Public Service Commission (NPSC) | Nebraska Gas
Public Utilities, General Disclosures [Line Items]
Tax Cuts and Jobs Act, Income Tax Expense (Benefit)		$ 2,900
Nebraska Publc Service Commission (NPSC) | Nebraska Gas
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Equity Capital Structure, Percentage	50.00%
Public Utilities, Approved Debt Capital Structure, Percentage	50.00%
Public Utilities, Approved Return on Equity, Percentage	9.50%
Public Utilities, Term Extension of System Saftey and Integrity Rider	5 years
Rate Review Filed with the Regulatory Agency | Colorado Public Utilities Commission (CPUC) | Colorado Gas
Public Utilities, General Disclosures [Line Items]
Public Utilities, Term Extension of System Saftey and Integrity Rider			5 years
Rate Review Filed with the Regulatory Agency | Nebraska Publc Service Commission (NPSC) | Nebraska Gas
Public Utilities, General Disclosures [Line Items]
Public Utilities - Length of Natural Gas Pipeline to Receive Infrastructure Investments | mi		13,000
Public Utilities Amount of System Safety and Integrety Rider Moved to Base Rates	$ 4,600
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 6,500
Rate Review Dismissed by Regulatory Agency | Colorado Public Utilities Commission (CPUC) | Colorado Gas
Public Utilities, General Disclosures [Line Items]
Public Utilities - Length of Natural Gas Pipeline to Receive Infrastructure Investments | mi				7,000

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Public Utilities Amount of System Safety and Integrety Rider Moved to Base Rates

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Settlement of plan to provide TCJA-related customer billing credits to its customers. The billing credits, which represent a disposition of excess deferred income tax benefits resulting from the TCJA, will be delivered to customers in the next fiscal year.

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Amount of income tax expense (benefit) from effect of Tax Cuts and Jobs Act.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32639-109319

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