CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 22,501	$ 16,142
Marketable securities	94,084	114,967
Accounts receivable, net of allowance for doubtful accounts of $1,821 and $1,816 as of March 31, 2020 and December 31, 2019, respectively	43,017	37,136
Restricted cash	70,087	70,087
Prepaid expenses and other current assets	12,139	10,991
Total current assets	241,828	249,323
Property and equipment, net	69,069	60,037
Goodwill	348	372
Intangible assets, net	1,089	1,125
Other assets	11,512	10,112
Total assets	323,846	320,969
Current liabilities:
Accounts payable	9,457	4,602
Accrued expenses	20,218	19,878
Current portion of long-term debt	5,291	4,472
Other current liabilities	5,430	8,169
Total current liabilities	40,396	37,121
Long-term debt, less current portion	26,043	25,158
Other long-term liabilities	1,357	1,038
Total liabilities	67,796	63,317
Commitments and contingencies (Note 9)
Stockholders’ equity:
Class A and Class B common stock	2	2
Additional paid-in capital	459,360	449,463
Accumulated other comprehensive income	687	196
Accumulated deficit	(203,999)	(192,009)
Total stockholders’ equity	256,050	257,652
Total liabilities and stockholders’ equity	$ 323,846	$ 320,969