Debt Issuance Costs - Additional Information (Detail) (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
Debt Issuance Costs [Line Items]
Net debt issuance costs	$ 11.9		$ 11.9		$ 13.9
Debt issuance costs			4.8
Amortization of debt issuance costs	0.5	0.7	1.8	2.2
Extinguished Indebtedness
Debt Issuance Costs [Line Items]
Debt issuance cost charged to interest expense			5.0
Other Current Assets
Debt Issuance Costs [Line Items]
Net debt issuance costs	$ 2.2		$ 2.2		$ 3.1