Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash Flows from Operating Activities:
Net loss	$ (15,681)	$ (14,232)	$ (11,172)
Adjustments to reconcile net loss from continuing operations to net cash (used in) provided by operating activities:
Depreciation and amortization	4,942	3,128	3,516
Stock-based compensation	5,402	4,178	5,575
Severance and related costs			29
Change in fair value of warrant liability	(3)	124	125
Other			2
Changes in assets and liabilities:
Receivables	(1,403)	(1,076)	184
Prepaid expenses	(623)	(85)	739
Other assets	910	192	(112)
Accounts payable	(29)	352	(29)
Accrued compensation and related costs	520	397	509
Unearned revenue	(2,416)	310	1,854
Other liabilities	1,992	(222)	330
Total Adjustments	9,292	7,298	12,722
Net cash (used in) provided by operating activities	(6,389)	(6,934)	1,550
Cash Flows from Investing Activities:
Capital expenditures	(4,917)	(766)	(1,233)
Intangible assets	(921)	(251)	(239)
Net cash used in investing activities	(5,838)	(1,017)	(1,472)
Cash Flows from Financing Activities:
Proceeds from issuance of common stock, net	15,942	11,138	5,621
Proceeds from line of credit	15,000	7,000	2,400
Repayments from line of credit	(15,000)	(7,000)	(6,096)
Principal payments under capital lease obligations	(2,116)	(1,701)	(2,117)
Acquisition of treasury stock, net	(874)	(797)	(1,055)
Proceeds from stock compensation and employee stock purchase plans, net	453	165	138
Proceeds from issuance of stock warrants			4
Net cash provided by (used in) financing activities	13,405	8,805	(1,105)
Effect of exchange rate changes on cash and cash equivalents	(9)	(8)
Increase (decrease) in cash and cash equivalents	1,169	846	(1,027)
Cash and cash equivalents, beginning of period	14,238	13,392	14,419
Cash and cash equivalents, end of period	15,407	14,238	13,392
Non-Cash Investing and Financing Transactions:
Capital lease obligations incurred	2,737	1,692	2,973
Capital equipment purchased on credit	2,737	1,692	2,973
Fair value of warrants classified as liability		380	785
Fair value of intellectual property purchase liability	1,958
Supplemental Disclosures of Cash Flow Information:
Interest paid	$ 314	$ 266	$ 403