Common Equity (Tables)

9 Months Ended

Sep. 30, 2018

Equity [Abstract]

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

The following table calculates basic and diluted earnings per share for the Company.

	Three Months Ended September 30,				Nine Months Ended September 30,
(In millions except per share data)	2018		2017		2018		2017
Net income	$	205.1	$	183.4	$	370.8	$	324.2
Average common shares outstanding:
Basic average common shares outstanding	199.7		199.7		199.7		199.7
Effect of dilutive securities:
Contingently issuable shares (performance and restricted stock units)	0.9		0.4		0.7		0.3
Diluted average common shares outstanding	200.6		200.1		200.4		200.0
Basic earnings per average common share	$	1.03	$	0.92	$	1.86	$	1.62
Diluted earnings per average common share	$	1.02	$	0.92	$	1.85	$	1.62
Anti-dilutive shares excluded from earnings per share calculation	—		—		—		—