Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2012

Earnings Per Share [Abstract]

Computation of basic and diluted net income per common share

The following table sets forth the computation of basic and diluted net income per common share for the years ending December 31 (in millions, except per share data):

	2012		2011		2010
Numerator:
Net income	$	137.3	$	110.8	$	80.8
Numerator for basic earnings per share — income available to common shareholders	$	137.3	$	110.8	$	80.8
Effect of dilutive securities:
After-tax interest expense on convertible securities	—		—		0.2
Numerator for diluted earnings per share — income available to common shareholders	$	137.3	$	110.8	$	81.0
Denominator:
Denominator for basic earnings per share — weighted average shares	46.8		46.4		46.1
Effect of dilutive securities:
Equity compensation plans	0.7		0.7		0.5
Convertible preferred stock	0.1		0.1		0.1
Convertible securities	—		—		0.3
Denominator for diluted earnings per share — adjusted weighted average and assumed conversion	47.6		47.2		47.0
Basic earnings per share	$	2.93	$	2.39	$	1.75
Diluted earnings per share	$	2.88	$	2.35	$	1.72