Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended					6 Months Ended			6 Months Ended
	Jun. 30, 2013 Customer	Jun. 30, 2012	Jun. 30, 2013 Customer	Jun. 30, 2012	Dec. 31, 2012 Customer	Jun. 30, 2013 Product Warranty	Dec. 31, 2012 Product Warranty	Aug. 31, 2009 2009 Unit Offering Warrant	Nov. 30, 2010 2010 Unit Offering Warrant	Jun. 30, 2013 Maximum	Jun. 30, 2013 Minimum	Dec. 31, 2012 Minimum	Jun. 30, 2013 Minimum Available-for-sale Securities
Summary Of Significant Accounting Policies [Line Items]
Deferred revenue	$ 153,000		$ 153,000		$ 77,000
Highly liquid investments, original maturities										3 months
Short-term investments, original maturities										1 year	3 months		1 year
Number of major customers representing outstanding trade receivables	4		4		3
Cumulative outstanding trade receivables percentage by major customers	64.00%		64.00%		59.00%						10.00%	10.00%
Life of inventory			2 years
Protracted length of inventory			1 year
Estimated useful life of property and equipment										5 years	3 years
Estimated useful life of intangible assets			10 years
Impairment charges on long-lived assets	0	0	0	0
Foreign currency gains (losses)	(157,000)	(611,000)	(211,000)	(240,000)
Warrants to purchase an aggregate shares of common stock								2.4	3.7
Derecognition of tax positions, Maximum										50.00%
Company's tax years subject to examination by the taxing jurisdictions										2012	1998
Unrecognized Tax Benefits	0		0		0
Current asset, warrant claim	200,000		200,000		2,038,000	0	1,800,000
Inventory write down					$ 1,700,000
Period of warranty			1 year