Schedule of Future Minimum Lease Payments Required Under Operating Leases (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Property, Plant and Equipment [Line Items]
2012	$ 396	$ 1,456
2013	1,580	1,580
2014	1,495	1,495
2015	1,501	1,501
2016	1,464	1,464
Thereafter	1,779	1,779
Total	$ 8,215	$ 9,275