Debt - Summary of Long-term Debt (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Debt [Line Items]
Total debt	$ 62.4	$ 59.8	$ 62.5
Less current portion	0.3	0.6
Long-term debt	62.1	59.2	62.5
Revolving credit facility [Member]
Debt [Line Items]
Total debt	61.5	59.1	62.4
Other obligations [Member]
Debt [Line Items]
Total debt	$ 0.9	$ 0.7	$ 0.1