Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended
	May 05, 2010	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Commitments And Contingencies Disclosure [Line Items]
Agreement period not to refile claims	90 days
Operating Leases, Future Minimum Payments Due, Total		$ 5.7		$ 5.7
Rent expense		$ 0.5	$ 0.6	$ 1.7	$ 1.7