WUTC (Details 5) - Natural gas rate proceeding [Member] - WUTC - USD ($) $ in Millions	May 31, 2019	Mar. 29, 2019	Mar. 28, 2019
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount			$ 48.0
Public utilities, requested rate increase (decrease), amount	$ 1.6	$ 12.7
Public utilities, requested rate increase (decrease), percentage	0.70%	5.50%

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