CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 60,333	$ 51,281
Marketable securities	16,364	11,435
Accounts receivable, net of allowance for doubtful accounts of $388 and $900 at December 31, 2017 and December 31, 2016, respectively	28,800	22,535
Deferred commissions	2,376	1,864
Other receivables	975	1,545
Prepaid expenses	6,444	9,382
Total current assets	115,292	98,042
Property and equipment, net	40,444	42,590
Intangible assets, net	1,118	1,012
Other assets	861	1,499
Total assets	157,715	143,143
Current liabilities
Accounts payable	3,060	849
Accrued expenses and other current liabilities	20,212	20,695
Deferred revenue	104,684	76,016
Deferred government grant obligation	217	1,022
Current portion of capital lease and financing obligations	1,168	1,285
Current portion of long-term debt	0	20
Total current liabilities	129,341	99,887
Deferred revenue	22,709	21,485
Deferred government grant obligation	278	1,000
Other long-term liabilities	3,896	4,100
Capital lease and financing obligations	18,425	19,743
Long-term debt	0	53
Total liabilities	174,649	146,268
Stockholders’ deficit
Preferred stock, $0.001 par value per share, 100,000,000 shares authorized, no shares issued and outstanding	0	0
Additional paid-in-capital	248,289	217,454
Accumulated deficit	(265,337)	(220,911)
Accumulated other comprehensive income	72	291
Total stockholders’ deficit	(16,934)	(3,125)
Total liabilities and stockholders’ deficit	157,715	143,143
Class A Common Stock
Stockholders’ deficit
Common stock	32	30
Class B Common Stock
Stockholders’ deficit
Common stock	$ 10	$ 11

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.