Restructuring Charges - Schedule of Restructuring Activities (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012
Restructuring Cost and Reserve [Line Items]
Restructuring Cost, Beginning Balance		$ 1.0
Restructuring charges	21.0	21.0
Cash Utilized, Net		(1.1)
Non Utilized, Net
Restructuring Cost, Ending Balance	20.9	20.9
2012 Restructuring Programs [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges		19.6
Cash Utilized, Net		(0.1)
Non Utilized, Net
Restructuring Cost, Ending Balance	19.5	19.5
2012 Restructuring Programs [Member] | Other Restructuring Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1.4
Cash Utilized, Net		(0.5)
Non Utilized, Net
Restructuring Cost, Ending Balance	0.9	0.9
Other Restructuring Programs [Member] | Other Restructuring Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Cost, Beginning Balance		1.0
Cash Utilized, Net		(0.5)
Non Utilized, Net
Restructuring Cost, Ending Balance	$ 0.5	$ 0.5