CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 664,334	$ 654,152
Accounts receivable, net of allowances of $5,837 and $5,344 as of June 30, 2021 and December 31, 2020, respectively	89,807	80,423
Prepaid expenses and other current assets	19,348	14,236
Total current assets	773,489	748,811
Operating lease right of use assets (Note 9)	307	614
Property and equipment, net (Note 6)	115,647	106,055
Contract acquisition costs	43,462	41,021
Intangibles, net (Note 5)	10,970	10,927
Goodwill (Note 5)	95,116	95,192
Deferred tax assets	3,600	2,032
Other assets	1,166	1,780
Total assets	1,043,757	1,006,432
Current liabilities:
Accounts payable	8,106	14,115
Accrued expenses and other current liabilities (Note 7)	97,567	99,870
Deferred revenue (Note 2)	107,671	88,848
Operating lease liability (Note 9)	2,711	5,718
Total current liabilities	216,055	208,551
Deferred revenue, net of current portion (Note 2)	489	409
Convertible senior notes, net (Note 8)	556,032	538,432
Operating lease liability, net of current portion (Note 9)	3,250	7,180
Deferred tax liability	1,782	1,622
Other liabilities	4,457	6,304
Total liabilities	782,065	762,498
Commitments and contingencies (Note 11)
Stockholders’ equity:
Preferred stock, $0.001 par value - 5,000,000 shares authorized, none issued	0	0
Common stock, $0.001 par value - 200,000,000 shares authorized, 72,017,145 and 70,264,265 shares issued, 69,307,315 and 67,554,435 shares outstanding as of June 30, 2021 and December 31, 2020, respectively	72	70
Additional paid-in capital	696,923	635,672
Treasury stock - 2,709,830 shares	(3)	(3)
Accumulated deficit	(434,199)	(391,885)
Accumulated other comprehensive (loss) income	(1,101)	80
Total stockholders’ equity	261,692	243,934
Total liabilities and stockholders’ equity	$ 1,043,757	$ 1,006,432