WUTC (Details 5) - Pending Rate Case [Member] - Gas Distribution [Member] - WUTC [Member] - Cascade Natural Gas [Member] - USD ($) $ in Millions	Jan. 08, 2021	Jul. 24, 2020	Jun. 19, 2020
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 13.8
Public Utilities, Requested Rate Increase (Decrease), Percentage			5.30%
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount	$ 7.4	$ 14.3
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage	2.80%	5.50%

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Amount of public utility's amended requested rate increase (decrease) with regulatory agency.

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Percentage of public utility's amended requested rate increase (decrease) with regulatory agency.

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Amount of public utility's requested rate increase (decrease) with regulatory agency.

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Percentage of public utility's requested rate increase (decrease) with regulatory agency.

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