Common Equity (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

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

Basic and diluted earnings per share for the Company were calculated as follows:

(In millions except per share data)	2018		2017		2016
Net income	$	425.5	$	619.0	$	338.2
Average common shares outstanding:
Basic average common shares outstanding	199.7		199.7		199.7
Effect of dilutive securities:
Contingently issuable shares (performance and restricted stock units)	0.8		0.3		0.2
Diluted average common shares outstanding	200.5		200.0		199.9
Basic earnings per average common share	$	2.13	$	3.10	$	1.69
Diluted earnings per average common share	$	2.12	$	3.10	$	1.69
Anti-dilutive shares excluded from earnings per share calculation	—		—		—