Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Statement of Cash Flows [Abstract]
Net loss	$ (3,962)	$ (8,018)
Adjustments to reconcile net loss to net cash provided by (used in) operations:
Depreciation	83	158
Amortization of intangible assets	32	33
Non-cash share-based compensation expense	190	305
Loss on warrant exchange	0	4,967
Inventory write-downs	139	0
Other non-cash adjustments	(15)	(15)
Change in:
Accounts receivable, net	191	(111)
Inventory	(455)	0
Other current and non-current assets	(46)	85
Accounts payable	381	(274)
Accrued liabilities	207	272
Deferred revenue	8,126	0
Billings on uncompleted contracts in excess of related costs	179	(333)
Net cash provided by (used in) operating activities	5,050	(2,931)
Cash flows from investing activities
Purchases of property and equipment	(69)	(77)
Net cash used in investing activities	(69)	(77)
Cash flows from financing activities
Principal payments under capital leases and long-term debt	0	(10)
Net proceeds from issuance of common stock and warrants	3,355	12,981
Net cash provided by financing activities	3,355	12,971
Change in cash and cash equivalents	8,336	9,963
Cash and cash equivalents, at beginning of period	8,349	5,375
Cash and cash equivalents, at end of period	16,685	15,338
Supplemental disclosure of cash flow information
Cash paid for interest	1	0
Supplemental schedule of non-cash investing and financing activities
Non-cash additions to property and equipment	246	0
Issuance of common stock for exchange of warrants	$ 0	$ 9,869