COMMON EQUITY - DIVIDEND RESTRICTIONS (Details) $ in Millions	12 Months Ended
Dec. 31, 2021 USD ($)
Dividend Payment Restrictions
Restricted retained earnings	$ 472
Public Service Commission of Wisconsin \| Minimum
Dividend Payment Restrictions
Common equity ratio required to be maintained (as a percent)	52.50%

A segregation of retained earnings which is unavailable for dividend distribution. Includes also retained earnings appropriated for loss contingencies.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant