INCOME TAXES (Tables)

9 Months Ended

Sep. 30, 2020

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 September 30, 2020				Three Months Ended September 30, 2019
(in millions)	Amount		Effective Tax Rate		Amount		Effective Tax Rate
Statutory federal income tax	$	20.1	21.0	%	$	15.1	21.0	%
State income taxes net of federal tax benefit	5.9		6.2	%	5.1		7.1	%
Federal excess deferred tax amortization – Wisconsin unprotected	(4.3)		(4.5)	%	—		—	%
Federal excess deferred tax amortization	(1.8)		(1.9)	%	(2.5)		(3.4)	%
Other	(0.3)		(0.4)	%	(0.7)		(1.1)	%
Total income tax expense	$	19.6	20.4	%	$	17.0	23.6	%

	Nine Months Ended September 30, 2020				Nine Months Ended September 30, 2019
(in millions)	Amount		Effective Tax Rate		Amount		Effective Tax Rate
Statutory federal income tax	$	50.5	21.0	%	$	37.8	21.0	%
State income taxes net of federal tax benefit	14.7		6.1	%	11.8		6.5	%
Federal excess deferred tax amortization – Wisconsin unprotected	(11.0)		(4.6)	%	—		—	%
Federal excess deferred tax amortization	(4.5)		(1.9)	%	(5.0)		(2.8)	%
Other	(1.3)		(0.5)	%	(1.8)		(0.9)	%
Total income tax expense	$	48.4	20.1	%	$	42.8	23.8	%