Noncontrolling Interests in Consolidated Affiliates (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Summary financial statistics - statement of operations and cash flows, consolidated affiliates
Sales	$ 771.3	$ 776.6	$ 2,284.0	$ 2,357.7
Income before taxes	109.5	111.4	312.9	309.0
Net income	69.7	76.0	206.2	207.0
Noncontrolling interests in net income	0.3	0.5	1.1	1.3
Summary financial statistics - balance sheet information, consolidated affiliates
Other current assets	140.4		140.4		78.4
Total assets	5,230.0		5,230.0		5,090.2
Total liabilities	4,618.1		4,618.1		4,771.9
Shareholders' equity	611.9	402.2	611.9	402.2	318.3	167.5
Noncontrolling interests in shareholders' equity	10.1		10.1		9.9
Joint ventures
Summary financial statistics - statement of operations and cash flows, consolidated affiliates
Sales	24.1	25.3	78.0	77.0
Income before taxes	4.8	1.8	5.8	5.9
Net income	3.6	1.5	4.8	5.0
Noncontrolling interests in net income	0.3	0.5	1.1	1.3
Summary financial statistics - balance sheet information, consolidated affiliates
Cash	10.6		10.6		5.7
Other current assets	35.8		35.8		41.6
Total assets	78.6		78.6		73.8
Total liabilities	53.0		53.0		47.2
Shareholders' equity	$ 25.6		$ 25.6		$ 26.6