Noncontrolling Interests in Consolidated Affiliates (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2011
Summary financial statistics - statement of operations and cash flows, consolidated affiliates
Sales	$ 709.9	$ 754.4
Income before taxes	81.3	92.1
Net income	53.2	61.3
Noncontrolling interests in net income	0.3	0.4
Summary financial statistics - balance sheet information, consolidated affiliates
Other current assets	94.4		78.4
Total assets	5,049.4		5,090.2
Total liabilities	4,637.8		4,771.9
Shareholders' equity	411.6	259.4	318.3	167.5
Noncontrolling interests in shareholders' equity	10.4		9.9
Joint ventures
Summary financial statistics - statement of operations and cash flows, consolidated affiliates
Sales	24.6	23.4
Income before taxes	0.5	1.8
Net income	0.8	1.6
Noncontrolling interests in net income	0.3	0.4
Summary financial statistics - balance sheet information, consolidated affiliates
Cash	8.4		5.7
Other current assets	38.7		41.6
Total assets	76.8		73.8
Total liabilities	49.4		47.2
Shareholders' equity	$ 27.4		$ 26.6