CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 307,836	$ 334,635
Short-term investments	50,175	59,902
Accounts receivable, net of allowance for doubtful accounts of $768 and $786 at June 30, 2018 and December 31, 2017, respectively	95,659	81,189
Prepaid expenses and other current assets	10,275	8,737
Total current assets	463,945	484,463
Property and equipment, net	15,205	16,610
Intangible assets, net	64,080	46,490
Goodwill	102,665	80,506
Other assets	1,612	1,006
Total assets	647,507	629,075
Current liabilities:
Accounts payable	3,978	6,090
Accrued compensation and benefits	9,601	13,914
Other current liabilities	41,351	35,538
Deferred revenues	8,520	6,276
Contingent consideration related to acquisitions	24,500	18,500
Total current liabilities	87,950	80,318
Other non-current liabilities	3,404	3,205
Convertible senior notes, net	150,704	145,821
Contingent consideration related to acquisitions	14,582
Deferred tax liabilities	1,871	1,690
Total liabilities	258,511	231,034
Commitments and contingencies (Note 13)
Stockholders’ equity:
Preferred stock, $0.00001 par value—10,000,000 shares authorized and no shares issued or outstanding at June 30, 2018 and December 31, 2017
Common stock, $0.00001 par value—250,000,000 shares authorized; 95,020,958 and 93,199,718 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively	1	1
Additional paid-in capital	696,104	686,025
Accumulated other comprehensive loss	(818)	(700)
Accumulated deficit	(306,291)	(287,285)
Total stockholders’ equity	388,996	398,041
Total liabilities and stockholders’ equity	$ 647,507	$ 629,075

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.