Stockholders' Equity - Accumulated Other Comprehensive Loss Primarily Comprised of Accumulated Foreign Currency Translation Adjustments (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Equity [Abstract]
Unrealized tax benefits	$ 0.1	$ 0.1