Noncontrolling Interests in Consolidated Affiliates (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Summary financial statistics - statement of operations and cash flows, consolidated affiliates
Sales	$ 802.8	$ 826.7	$ 1,512.7	$ 1,581.1
Income before taxes	122.1	105.5	203.4	197.6
Net income	83.3	69.7	136.5	131.0
Noncontrolling interests in net income	0.5	0.4	0.8	0.8
Summary financial statistics - balance sheet information, consolidated affiliates
Other current assets	91.4		91.4		78.4
Total assets	5,165.5		5,165.5		5,090.2
Total liabilities	4,631.4		4,631.4		4,771.9
Shareholders' equity	534.1	288.6	534.1	288.6	318.3	167.5
Noncontrolling interests in shareholders' equity	10.5		10.5		9.9
Joint ventures
Summary financial statistics - statement of operations and cash flows, consolidated affiliates
Sales	29.3	28.3	53.9	51.7
Income before taxes	0.5	2.3	1.0	4.1
Net income	0.4	1.9	1.2	3.5
Noncontrolling interests in net income	0.5	0.4	0.8	0.8
Summary financial statistics - balance sheet information, consolidated affiliates
Cash	8.5		8.5		5.7
Other current assets	39.9		39.9		41.6
Total assets	81.1		81.1		73.8
Total liabilities	55.0		55.0		47.2
Shareholders' equity	$ 26.1		$ 26.1		$ 26.6