CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current Assets:
Cash and cash equivalents	$ 118,036	$ 216,226
Marketable securities	106,130	29,414
Accounts receivable, net of allowance for doubtful accounts of $834 and $763 as of June 30, 2016 and December 31, 2015, respectively	28,666	26,168
Prepaid expenses and other current assets	19,645	11,423
Total current assets	272,477	283,231
Marketable securities, noncurrent	51,625	22,336
Property and equipment, net	55,734	56,540
Goodwill and intangible assets, net	55,948	57,050
Other assets	4,157	3,529
Total assets	439,941	422,686
Current liabilities:
Accounts payable	6,481	9,332
Accrued liabilities	11,962	9,742
Accrued compensation and related benefits	15,183	14,115
Deferred revenue	101,042	84,210
Total current liabilities	134,668	117,399
Deferred revenue, noncurrent	1,316	1,405
Other liabilities	11,240	10,592
Total liabilities	147,224	129,396
Commitments and contingencies
Stockholders’ equity:
Preferred stock	0	0
Common stock	937	905
Additional paid-in capital	563,600	511,183
Accumulated other comprehensive loss	(1,823)	(2,225)
Accumulated deficit	(269,345)	(215,921)
Treasury stock at cost (0.5 million shares as of June 30, 2016 and December 31, 2015)	(652)	(652)
Total stockholders’ equity	292,717	293,290
Total liabilities and stockholders’ equity	$ 439,941	$ 422,686

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.