Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2014

Earnings Per Share [Abstract]

Computation of Basic and Diluted Income Per Common Share

The following table sets forth the computation of basic and diluted income per common share for the periods presented (dollars and shares in millions, except per share data).

	Year Ended December 31
	2014			2013		2012
Numerator:
Net income	$	392.6		$	441.3	$	160.2
Less: distributed and undistributed earnings allocated to participating securities	(5.7		)	—		—
Net income attributable to common shareholders	$	386.9		$	441.3	$	160.2
Denominator:
Weighted average basic common shares outstanding	97.0			96.6		96.4
Effect of dilutive securities	0.1			0.9		1.1
Diluted common shares outstanding	97.1			97.5		97.5
Basic income per common share	$	3.99		$	4.57	$	1.66
Diluted income per common share	$	3.99		$	4.52	$	1.64