INCOME TAXES (Tables)

3 Months Ended

Mar. 31, 2021

Income Tax Disclosure [Abstract]

Schedule of effective income tax rate reconciliation

The provision for income taxes differs from the amount of income tax determined by applying the applicable United States statutory federal income tax rate to income before income taxes as a result of the following:

	Three Months Ended March 31, 2021				Three Months Ended March 31, 2020
(in millions)	Amount		Effective Tax Rate		Amount		Effective Tax Rate
Statutory federal income tax	$	122.8	21.0	%	$	113.9	21.0	%
State income taxes net of federal tax benefit	36.9		6.3	%	34.0		6.3	%
PTCs	(34.0)		(5.8)	%	(18.4)		(3.4)	%
Federal excess deferred tax amortization – Wisconsin unprotected	(30.3)		(5.2)	%	(22.1)		(4.1)	%
Federal excess deferred tax amortization	(14.6)		(2.5)	%	(13.0)		(2.4)	%
Uncertain tax positions	(8.2)		(1.4)	%	—		—	%
Other	2.3		0.4	%	(4.4)		(0.8)	%
Total income tax expense	$	74.9	12.8	%	$	90.0	16.6	%