Earnings Per Share and Common Stock (Tables)

9 Months Ended

Sep. 30, 2018

Earnings Per Share [Abstract]

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

			2018					2017
Reconciliation of Basic and Diluted			Dilutive					Dilutive
Earnings Per Share	Basic		Securities	Diluted		Basic		Securities	Diluted
Millions Except Per Share Amounts
Quarter ended September 30,
Net Income		$30.7			$30.7		$44.9			$44.9
Average Common Shares	51.4		0.2	51.6		51.0		0.2	51.2
Earnings Per Share		$0.59			$0.59		$0.88			$0.88
Nine Months Ended September 30,
Net Income		$113.0			$113.0		$130.8			$130.8
Average Common Shares	51.3		0.2	51.5		50.7		0.2	50.9
Earnings Per Share		$2.20			$2.19		$2.58			$2.57