CREDIT LOSSES - ROLLFORWARD OF ALLOWANCES (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 190.7	$ 213.8	$ 193.5	$ 199.3
Provision for credit losses	23.7	11.1	49.6	32.1
Write-offs charged against the allowance	(59.3)	(51.5)	(124.2)	(105.0)
Recovery of amounts previously written off	17.9	17.7	37.1	29.1
Balance at end of period	166.9	178.7	166.9	178.7
Change in allowance for credit losses			26.6	20.6
Uncollectible expense
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Provision for credit losses deferred for future recovery or refund	(6.1)	(12.4)	10.9	23.2
Public Utilities
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period			193.5
Balance at end of period	166.9		166.9
Wisconsin | Public Utilities
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	83.0	90.9	77.4	82.0
Provision for credit losses	9.8	6.7	23.6	17.9
Write-offs charged against the allowance	(35.9)	(29.1)	(71.5)	(58.0)
Recovery of amounts previously written off	10.4	11.8	22.1	18.0
Balance at end of period	68.7	76.4	68.7	76.4
Wisconsin | Public Utilities | Uncollectible expense
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Provision for credit losses deferred for future recovery or refund	1.4	(3.9)	17.1	16.5
Illinois | Public Utilities
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	104.6	116.5	109.7	111.0
Provision for credit losses	12.2	4.8	27.3	13.3
Write-offs charged against the allowance	(22.3)	(21.3)	(50.3)	(44.3)
Recovery of amounts previously written off	6.2	5.5	12.7	10.3
Balance at end of period	93.2	97.0	93.2	97.0
Illinois | Public Utilities | Uncollectible expense
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Provision for credit losses deferred for future recovery or refund	(7.5)	(8.5)	(6.2)	6.7
Other States | Public Utilities
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	3.1	6.4	6.4	6.3
Provision for credit losses	1.7	(0.4)	(1.3)	0.9
Write-offs charged against the allowance	(1.1)	(1.1)	(2.4)	(2.7)
Recovery of amounts previously written off	1.3	0.4	2.3	0.8
Balance at end of period	5.0	5.3	5.0	5.3
Other States | Public Utilities | Uncollectible expense
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Provision for credit losses deferred for future recovery or refund	$ 0.0	$ 0.0	$ 0.0	$ 0.0