QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Tables)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Schedule of quarterly financial information (unaudited)

(in millions)	First Quarter		Second Quarter		Third Quarter		Fourth Quarter		Total
2020
Operating revenues	$	369.4	$	312.8	$	367.7	$	357.2	$	1,407.1
Operating income	92.9		67.4		102.8		45.1		308.2
Net income	68.2		47.7		76.3		29.4		$	221.6
2019
Operating revenues	$	395.8	$	320.9	$	352.3	$	342.9	$	1,411.9
Operating income	60.6		59.8		78.0		69.2		267.6
Net income	40.9		41.5		55.0		47.3		184.7