Quarterly Financial Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information (unaudited)

(in millions, except per share amounts)	First Quarter		Second Quarter		Third Quarter		Fourth Quarter		Total
2019
Operating revenues	$	2,377.4	$	1,590.2	$	1,608.0	$	1,947.5	$	7,523.1
Operating income	542.8		314.6		310.9		363.1		1,531.4
Net income attributed to common shareholders	420.1		235.7		234.3		243.9		1,134.0
Earnings per share *
Basic	$	1.33	$	0.75	$	0.74	$	0.77	$	3.60
Diluted	1.33		0.74		0.74		0.77		3.58
2018
Operating revenues	$	2,286.5	$	1,672.5	$	1,643.7	$	2,076.8	$	7,679.5
Operating income	545.1		330.8		302.7		289.8		1,468.4
Net income attributed to common shareholders	390.1		231.0		233.2		205.0		1,059.3
Earnings per share *
Basic	$	1.24	$	0.73	$	0.74	$	0.65	$	3.36
Diluted	1.23		0.73		0.74		0.65		3.34

*

Earnings per share for the individual quarters may not total the year ended earnings per share amount because of changes to the average number of shares outstanding and changes in incremental issuable shares throughout the year.