CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 5,640	$ 3,110
Short-term investments	14,598	20,439
Accounts receivable, net	729	177
Inventories, net	1,597	881
Prepaid expenses and other	701	887
Total current assets	23,265	25,494
Long-term investments		2,245
Property and equipment, net	1,630	854
Goodwill	23,134	23,134
Intangible assets, net	334	655
Other	329	244
Total assets	48,692	52,626
Current liabilities
Accounts payable	940	495
Accrued expenses and other	2,664	2,350
Total current liabilities	3,604	2,845
Long-term liabilities	$ 247	$ 241
Commitments and contingencies (Note 10)
Stockholders' equity
Preferred stock, $0.01 par value; 20,000 shares authorized; none issued and outstanding
Common stock, $0.01 par value; 120,000 shares authorized; 65,496 shares and 49,793 shares issued and outstanding at December 31, 2015 and 2014, respectively	$ 655	$ 498
Additional paid-in capital	226,174	199,541
Accumulated other comprehensive loss	(16)	(10)
Accumulated deficit	(181,972)	(150,489)
Total stockholders' equity	44,841	49,540
Total liabilities and stockholders' equity	$ 48,692	$ 52,626

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Name:	us-gaap_AccountsPayableCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.