CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 1,995,482	$ 553,398
Marketable securities	2,250	157,649
Restricted cash	32,128	93,880
Accounts receivable	56,898	262,012
Unbilled services	45,295	0
Prepaid expenses and other current assets	114,731	181,264
Total current assets	2,246,784	1,248,203
Restricted cash	1,460	1,460
Property and equipment, net	192,044	179,954
Intangible assets, net	5,270	5,725
Goodwill	130,879	135,379
Other non-current assets	31,929	11,758
Total assets	2,608,366	1,582,479
Current liabilities:
Accounts payable	113,605	54,332
Accrued expenses	148,611	142,468
Deferred revenue	822,809	273,228
Current portion of finance lease liabilities	121,144	105,862
Other current liabilities	2,386	3,782
Total current liabilities	1,208,555	579,672
Convertible notes payable	322,390	322,035
Non-current finance lease liabilities	16,696	40,083
Other non-current liabilities	21,598	13,480
Total liabilities	1,569,239	955,270
Commitments and contingencies
Preferred stock, $0.01 par value, 2,000,000 shares authorized at March 31, 2021 and December 31, 2020; no shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively	0	0
Stockholders' equity:
Common stock, $0.01 par value, 600,000,000 shares authorized at March 31, 2021 and December 31, 2020; and 74,470,583 shares issued and 74,061,594 shares outstanding at March 31, 2021 and 71,350,365 shares issued and 70,953,739 shares outstanding at December 31, 2020	745	714
Additional paid-in capital	3,180,114	2,535,476
Accumulated deficit	(2,096,918)	(1,874,199)
Treasury stock, 408,989 shares, cost basis at March 31, 2021 and 396,626 shares, cost basis at December 31, 2020	(44,457)	(41,806)
Accumulated other comprehensive (loss) income	(357)	7,024
Total stockholders’ equity	1,039,127	627,209
Total liabilities and stockholders’ equity	$ 2,608,366	$ 1,582,479