Organization and Basis for Presentation - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
Inventory [Member]
Organization And Basis Of Presentation [Line Items]
Prior period adjustments		$ 0.4	$ 0.2
Cost of Sales [Member]
Organization And Basis Of Presentation [Line Items]
Prior period adjustments	0.4	0.2	0.2
Net Income [Member]
Organization And Basis Of Presentation [Line Items]
Prior period adjustments	$ 0.3