Property and Equipment - Schedule of Property and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Property Plant And Equipment [Abstract]
Computer equipment and purchased software	$ 3,573	$ 3,748
Machinery and equipment	704	654
Furniture and fixtures	578	546
Leasehold improvements	905	884
Total	5,760	5,832
Less accumulated depreciation	(4,776)	(4,551)
Property and equipment, net	$ 984	$ 1,281