Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 503,804	$ 173,617
Short-term investments	101,996	138,839
Accounts receivable, net of allowance for doubtful accounts of $2,869 and $3,251 at March 31, 2021 and December 31, 2020, respectively	76,714	111,599
Deferred contract acquisition and fulfillment costs, current portion	22,598	21,536
Prepaid expenses and other current assets	28,943	27,844
Total current assets	734,055	473,435
Long-term investments	11,133	10,124
Property and equipment, net	51,141	53,114
Operating lease right-of-use assets	64,965	67,178
Deferred contract acquisition and fulfillment costs, non-current portion	43,997	43,103
Goodwill	253,324	213,601
Intangible assets, net	52,708	44,296
Other assets	11,370	8,271
Total assets	1,222,693	913,122
Current liabilities:
Accounts payable	4,296	3,860
Accrued expenses	47,806	61,677
Operating lease liabilities, current portion	9,261	9,612
Deferred revenue, current portion	282,245	278,585
Other current liabilities	127	0
Total current liabilities	343,735	353,734
Convertible senior notes, net	855,709	378,586
Operating lease liabilities, non-current portion	73,466	75,737
Deferred revenue, non-current portion	28,833	31,365
Other long-term liabilities	2,175	2,164
Total liabilities	1,303,918	841,586
Stockholders’ equity (deficit):
Preferred stock, $0.01 par value per share; 10,000,000 shares authorized at March 31, 2021 and December 31, 2020; 0 shares issued at March 31, 2021 and December 31, 2020	0	0
Common stock, $0.01 par value per share; 100,000,000 shares authorized at March 31, 2021 and December 31, 2020; 55,578,120 and 52,712,084 shares issued at March 31, 2021 and December 31, 2020, respectively; 55,091,312 and 52,225,276 shares outstanding at March 31, 2021 and December 31, 2020, respectively	551	522
Treasury stock, at cost, 486,808 shares at March 31, 2021 and December 31, 2020	(4,764)	(4,764)
Additional paid-in-capital	542,415	692,603
Accumulated other comprehensive loss	112	454
Accumulated deficit	(619,539)	(617,279)
Total stockholders’ equity (deficit)	(81,225)	71,536
Total liabilities and stockholders’ equity (deficit)	$ 1,222,693	$ 913,122