Earnings Per Share and Common Stock (Tables)

6 Months Ended

Jun. 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 June 30,
Net Income		$31.3			$31.3		$36.9			$36.9
Average Common Shares	51.3		0.2	51.5		50.9		0.2	51.1
Earnings Per Share		$0.61			$0.61		$0.73			$0.72
Six Months Ended June 30,
Net Income		$82.3			$82.3		$85.9			$85.9
Average Common Shares	51.2		0.2	51.4		50.5		0.2	50.7
Earnings Per Share		$1.61			$1.60		$1.70			$1.69