Stock-Based Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Stock-based compensation
Pre-tax compensation expense	$ 2.8	$ 3.6	$ 13.7	$ 13.5
Aggregate grant date fair value of stock options, restricted stock awards and performance share awards			16.9
2008 Executive Incentive Program
Stock-based compensation
Shares available for grant under the plan	3,074,840		3,074,840
Shares available for issuance under the plan	693,705		693,705
2005 Nonemployee Director Equity Plan
Stock-based compensation
Shares available for grant under the plan	267,466		267,466
Shares available for issuance under the plan	37,466		37,466
Stock options
Stock-based compensation
Pre-tax compensation expense	$ 1.2	$ 2.1	$ 3.6	$ 5.6
Stock options granted (in shares)			283,975
Maximum term life			10 years
Weighted-average assumptions used to estimate grant date fair value of stock options
Expected dividend yield (as a percent)			1.20%	1.50%
Expected life in years			5 years 8 months 16 days	5 years 9 months 11 days
Expected volatility (as a percent)			32.20%	36.00%
Risk-free interest rate (as a percent)			1.00%	0.90%
Weighted average fair value (in dollars per share)			$ 17.58	$ 14.57
Stock options | Awards 2008 and thereafter
Stock-based compensation
Portion of stock options vesting on the first anniversary			0.3333
Portion of stock options vesting on the second anniversary			0.3333
Portion of stock options vesting on the third anniversary			0.3333
Restricted stock awards
Stock-based compensation
Awards granted (in shares)			71,255
Performance share awards
Stock-based compensation
Awards granted (in shares)			71,255
Restricted Stock Units
Stock-based compensation
Awards granted (in shares)			11,592