Common Equity (Tables)

12 Months Ended

Dec. 31, 2016

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)	2016		2015		2014
Net income	$	338.2	$	271.3	$	395.8
Average Common Shares Outstanding
Basic average common shares outstanding	199.7		199.6		199.2
Effect of dilutive securities:
Contingently issuable shares (performance and restricted stock units)	0.2		—		0.7
Diluted average common shares outstanding	199.9		199.6		199.9
Basic Earnings Per Average Common Share	$	1.69	$	1.36	$	1.99
Diluted Earnings Per Average Common Share	$	1.69	$	1.36	$	1.98
Anti-dilutive shares excluded from earnings per share calculation	—		—		—