Accounting Policies (Details 5) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended			0 Months Ended	6 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jan. 26, 2011 Chief Executive Officer	Dec. 14, 2012 Chief Executive Officer	Dec. 31, 2012 Stock options	Dec. 31, 2011 Stock options	Dec. 31, 2010 Stock options	Dec. 31, 2012 Other stock-based plans	Dec. 31, 2011 Other stock-based plans	Dec. 31, 2010 Other stock-based plans
Stock-based compensation
Total unrecognized compensation costs related to unvested stock-based compensation arrangements	$ 15.6
Total weighted average remaining term of unrecognized compensation costs	2 years 7 months 6 days
Compensation cost recognized in selling, general and administrative expenses	5.8	5.3	4.7
Tax benefit recorded for the compensation expense						0.7	0.7	0.7	1.4	1.5	1.2
Impact on both basic and diluted net income per common share for recognition of total stock-based compensation expense (in dollars per share)	$ 0.10	$ 0.09	$ 0.08
Charges related to separation agreement with company's former CEO				6.3	1.5
Expected cash severance charge				3.3	0.7
Expected non-cash severance charge				$ 3.0	$ 0.8