CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 669,230	$ 649,666
Marketable securities	1,091,076	1,063,679
Accounts receivable, net of allowances of $8,811 and $2,851 as of December 31, 2020 and 2019, respectively	563,733	316,367
Prepaid expenses and other current assets	33,502	37,522
Total current assets	2,357,541	2,067,234
Property and equipment, net	69,375	91,992
Operating lease right-of-use assets	155,916	188,251
Goodwill and intangible assets, net	13,562	14,576
Restricted cash	9,110	25,339
Other assets	3,955	5,925
Total assets	2,609,459	2,393,317
Current liabilities:
Accounts payable	49,491	34,334
Accrued expenses and other current liabilities	155,340	141,823
Total current liabilities	204,831	176,157
Operating lease liabilities	139,321	173,392
Other liabilities	22,936	20,063
Total liabilities	367,088	369,612
Commitments and contingencies
Stockholders’ equity:
Common stock	6	6
Additional paid-in capital	4,574,934	4,229,778
Accumulated other comprehensive income	2,480	647
Accumulated deficit	(2,335,049)	(2,206,726)
Total stockholders’ equity	2,242,371	2,023,705
Total liabilities and stockholders’ equity	$ 2,609,459	$ 2,393,317