Property and Equipment Net (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Leasehold improvements	$ 5,628	$ 5,598
Machinery and equipment	1,751	1,594
Demonstration equipment	100	24
Office furniture	763	644
Computer equipment	651	550
Computer software	1,083	1,062
Construction-in-progress	155	55
Total property and equipment, gross	10,773	10,020
Accumulated depreciation and amortization	(8,584)	(8,322)
Total property and equipment, net	2,189	1,698
Consigned Equipment
Property, Plant and Equipment [Line Items]
Demonstration equipment	$ 642	$ 493