Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 204,434	$ 123,413
Short-term investments	36,384	116,158
Accounts receivable, net of allowance for doubtful accounts of $2,251 and $1,829 at March 31, 2020 and December 31, 2019, respectively	64,388	87,927
Deferred contract acquisition and fulfillment costs, current portion	17,486	17,047
Prepaid expenses and other current assets	19,624	20,051
Total current assets	342,316	364,596
Long-term investments	12,804	22,887
Property and equipment, net	50,075	50,670
Operating lease right-of-use assets	62,942	60,984
Deferred contract acquisition and fulfillment costs, non-current portion	34,289	34,213
Goodwill	97,866	97,866
Intangible assets, net	27,867	28,561
Other assets	5,518	5,136
Total assets	633,677	664,913
Current liabilities:
Accounts payable	10,062	6,836
Accrued expenses	26,486	41,021
Operating lease liabilities, current portion	8,866	7,179
Deferred revenue, current portion	219,432	231,518
Other current liabilities	35	119
Total current liabilities	264,881	286,673
Convertible senior notes, net	187,944	185,200
Operating lease liabilities, non-current portion	71,586	72,294
Deferred revenue, non-current portion	31,641	36,226
Other long-term liabilities	1,325	1,352
Total liabilities	557,377	581,745
Stockholders’ equity:
Preferred stock, $0.01 par value per share; 10,000,000 shares authorized at March 31, 2020 and December 31, 2019; 0 shares issued at March 31, 2020 and December 31, 2019	0	0
Common stock, $0.01 par value per share; 100,000,000 shares authorized at March 31, 2020 and December 31, 2019; 50,906,182 and 50,397,922 shares issued at March 31, 2020 and December 31, 2019, respectively; 50,419,374 and 49,911,114 shares outstanding at March 31, 2020 and December 31, 2019, respectively	504	499
Treasury stock, at cost, 486,808 shares at March 31, 2020 and December 31, 2019	(4,764)	(4,764)
Additional paid-in-capital	621,992	605,650
Accumulated other comprehensive (loss) income	(78)	213
Accumulated deficit	(541,354)	(518,430)
Total stockholders’ equity	76,300	83,168
Total liabilities and stockholders’ equity	$ 633,677	$ 664,913