CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 173,617	$ 123,413
Short-term investments	138,839	116,158
Accounts receivable, net of allowance for doubtful accounts of $3,251 and $1,829 at December 31, 2020 and 2019, respectively	111,599	87,927
Deferred contract acquisition and fulfillment costs, current portion	21,536	17,047
Prepaid expenses and other current assets	27,844	20,051
Total current assets	473,435	364,596
Long-term investments	10,124	22,887
Property and equipment, net	53,114	50,670
Operating lease right-of-use assets	67,178	60,984
Deferred contract acquisition and fulfillment costs, non-current portion	43,103	34,213
Goodwill	213,601	97,866
Intangible assets, net	44,296	28,561
Other assets	8,271	5,136
Total assets	913,122	664,913
Current liabilities:
Accounts payable	3,860	6,836
Accrued expenses	61,677	41,021
Operating lease liabilities, current portion	9,612	7,179
Deferred revenue, current portion	278,585	231,518
Other current liabilities	0	119
Total current liabilities	353,734	286,673
Convertible senior notes, net	378,586	185,200
Operating lease liabilities, non-current portion	75,737	72,294
Deferred revenue, non-current portion	31,365	36,226
Other long-term liabilities	2,164	1,352
Total liabilities	841,586	581,745
Stockholders’ equity:
Preferred stock, $0.01 par value per share; 10,000,000 shares authorized at December 31, 2020 and 2019; 0 shares issued and outstanding at December 31, 2020 and 2019	0	0
Common stock, $0.01 par value per share; 100,000,000 shares authorized at December 31, 2020 and 2019; 52,712,084 and 50,397,922 shares issued at December 31, 2020 and 2019, respectively; 52,225,276 and 49,911,114 shares outstanding at December 31, 2020 and 2019, respectively	522	499
Treasury stock, at cost, 486,808 shares at December 31, 2020 and 2019	(4,764)	(4,764)
Additional paid-in-capital	692,603	605,650
Accumulated other comprehensive loss	454	213
Accumulated deficit	(617,279)	(518,430)
Total stockholders’ equity	71,536	83,168
Total liabilities and stockholders’ equity	$ 913,122	$ 664,913

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, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business.