INCOME TAXES (Tables)

3 Months Ended

Mar. 31, 2019

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, 2019					Three Months Ended March 31, 2018
(in millions)	Amount			Effective Tax Rate		Amount			Effective Tax Rate
Statutory federal income tax	$	101.9		21.0	%	$	100.5		21.0	%
State income taxes net of federal tax benefit	31.0			6.4	%	29.9			6.2	%
Tax repairs	(29.6		)	(6.1	)%	(25.5		)	(5.3	)%
Wind production tax credits	(13.4		)	(2.8	)%	(3.8		)	(0.8	)%
Federal excess deferred tax amortization	(13.2		)	(2.7	)%	(15.5		)	(3.2	)%
Excess tax benefits – stock options	(7.2		)	(1.5	)%	(0.9		)	(0.2	)%
Other	(4.5		)	(0.9	)%	3.6			0.7	%
Total income tax expense	$	65.0		13.4	%	$	88.3		18.4	%