CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 109,370	$ 93,677
Marketable securities	137,576	131,190
Accounts receivable, net of allowance for doubtful accounts of $1,252 and $1,269 as of December 31, 2017 and 2016, respectively	57,096	37,343
Prepaid expenses and other current assets	24,165	17,608
Total current assets	328,207	279,818
Marketable securities, noncurrent	97,447	75,168
Property and equipment, net	59,157	62,731
Goodwill and intangible assets, net	67,034	53,296
Other assets	8,359	4,272
Total assets	560,204	475,285
Current liabilities:
Accounts payable	5,307	4,555
Accrued liabilities	21,876	19,106
Accrued compensation and related benefits	29,017	20,281
Deferred revenue	174,524	123,276
Total current liabilities	230,724	167,218
Deferred revenue, noncurrent	1,213	1,257
Other liabilities	6,626	7,382
Total liabilities	238,563	175,857
Commitments and contingencies (Note 7)
Stockholders’ equity:
Preferred stock, par value $0.01 per share: no shares issued or outstanding; 10.0 million shares authorized as of December 31, 2017 and 2016	0	0
Common stock, par value $0.01 per share: 400.0 million shares authorized; 103.1 million and 97.2 million shares issued; 103.1 million and 96.7 million shares outstanding as of December 31, 2017 and 2016, respectively	1,031	971
Additional paid-in capital	753,568	624,026
Accumulated other comprehensive loss	(2,372)	(5,197)
Accumulated deficit	(430,586)	(319,720)
Treasury stock, at cost; none and 0.5 million shares as of December 31, 2017 and 2016, respectively	0	(652)
Total stockholders’ equity	321,641	299,428
Total liabilities and stockholders’ equity	$ 560,204	$ 475,285

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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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.