Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
CURRENT ASSETS:
Cash and cash equivalents	$ 34,619	$ 34,346
Short-term investments	45,613	42,408
Accounts receivable, net of allowance for doubtful accounts of $27 and $61 as of June 30, 2017 and December 31, 2016, respectively	22,929	26,190
Inventories	14,982	12,629
Prepaid expenses and other current assets	7,128	6,289
Total current assets	125,271	121,862
Property and equipment, net	7,638	9,008
Goodwill	513	513
Other assets	5,375	5,100
Total assets	138,797	136,483
CURRENT LIABILITIES:
Accounts payable	14,663	10,762
Accrued liabilities	9,014	9,300
Debt, current	0	20,000
Deferred revenue, current	32,954	31,727
Total current liabilities	56,631	71,789
Debt, non-current	20,000	0
Deferred revenue, non-current	34,957	34,177
Other liabilities	1,795	1,829
Total liabilities	113,383	107,795
Commitments and contingencies (Note 5)
Stockholders’ equity:
Preferred stock, par value of $0.001 per share - 25,000,000 shares authorized as of June 30, 2017 and December 31, 2016; no shares issued and outstanding as of June 30, 2017 and December 31, 2016	0	0
Common stock, par value of $0.001 per share - 500,000,000 shares authorized as of June 30, 2017 and December 31, 2016; 53,871,669 and 52,245,252 shares issued and outstanding as of June 30, 2017 and December 31, 2016, respectively	54	52
Additional paid–in capital	268,929	258,063
Treasury stock - 573,406 and 364,627 shares as of June 30, 2017 and December 31, 2016, respectively	(3,159)	(2,139)
Accumulated other comprehensive loss	(38)	(31)
Accumulated deficit	(240,372)	(227,257)
Total stockholders’ equity	25,414	28,688
Total liabilities and stockholders’ equity	$ 138,797	$ 136,483

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).

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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.