CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 43,226	$ 58,750
Marketable securities	12,665	17,420
Accounts receivable, net of allowance for doubtful accounts of $837 and $713 at March 31, 2016 and December 31, 2015, respectively	16,470	15,647
Deferred commissions	1,383	1,368
Other receivables	1,042	818
Prepaid expenses and other current assets	4,063	3,875
Total current assets	78,849	97,878
Property and equipment, net	43,747	44,410
Intangible assets, net	936	896
Other assets	774	711
Total assets	124,306	143,895
Current liabilities
Accounts payable	4,156	5,138
Accrued expenses and other current liabilities	14,578	20,394
Deferred revenue	53,101	55,741
Deferred government grant obligation	1,023	985
Current portion of capital lease and financing obligations	1,732	1,808
Current portion of long-term debt	18	18
Total current liabilities	74,608	84,084
Deferred revenue	7,138	7,597
Deferred government grant obligation	1,708	1,996
Other long-term liabilities	3,491	3,343
Capital lease and financing obligations	20,727	21,083
Long-term debt	73	73
Total liabilities	107,745	118,176
Stockholders’ equity
Preferred stock, $0.001 par value per share, 100,000,000 shares authorized, no shares issued and outstanding	0	0
Additional paid-in-capital	205,284	202,371
Accumulated deficit	(188,979)	(176,934)
Accumulated other comprehensive income	215	241
Total stockholders’ equity	16,561	25,719
Total liabilities and stockholders’ equity	124,306	143,895
Class A Common Stock
Stockholders’ equity
Common stock	29	29
Class B Common Stock
Stockholders’ equity
Common stock	$ 12	$ 12