Regulatory Environment - MGU (Details) - MPSC - MGU - USD ($) $ in Millions	1 Months Ended
	Sep. 30, 2021	Jul. 31, 2020
Public Utilities, General Disclosures
Depreciation and interest expense approved for deferral		$ 5.0
Approved rate increase	$ 9.3
Approved rate increase (as a percent)	6.35%
Approved return on equity (as a percent)	9.85%
Approved common equity component average (as a percent)	51.50%
Recoverable planned capital investment	$ 31.7