CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net loss	$ (2,149)	$ (10,142)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	486	573
Stock-based compensation	446	552
Amortization of intangible assets	83	84
Impairment of goodwill	3,159
Amortization of debt issuance costs	30	33
Accrued interest	500	656
Gain on disposal of assets		(12)
Changes in assets and liabilities
Accounts receivable	(822)	(1,160)
Inventories	395	205
Prepaid expenses and other assets	782	(1,289)
Accounts payable	(30)	(390)
Deferred revenue and other liabilities	(2,469)	1,931
Net cash provided by (used in) operating activities	411	(8,959)
Cash flows from investing activities:
Purchases of property and equipment	(45)	(26)
Net proceeds from sale of assets		12
Proceeds from sales and maturities of marketable securities		2,604
Purchases of marketable securities		(1,602)
Net cash provided by (used in) investing activities	(45)	988
Cash flows from financing activities:
Issuance costs for sale of common stock	(12)
Taxes paid to net share settle equity awards	(46)
Proceeds from the issuance of common stock		1,989
Net cash provided by (used in) financing activities	(58)	1,989
Net increase (decrease) in cash and cash equivalents	308	(5,982)
Cash and cash equivalents at beginning of period	3,868	8,766
Cash and cash equivalents at end of period	4,176	2,784
Supplemental disclosure:
Issuance of convertible notes in settlement of accrued interest	$ 846	$ 854