Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 305,538	$ 340,678
Accounts receivable	8,609	10,471
Prepaid expenses and other current assets	3,482	3,681
Total current assets	317,629	354,830
Property and equipment, net	16,580	15,272
Other assets	5,569	6,133
Total Assets	339,778	376,235
Current Liabilities:
Accounts payable	335	2,172
Accrued expenses	9,156	7,999
Current portion of deferred revenue	15,678	21,188
Total current liabilities	25,169	31,359
Deferred revenue, net of current portion	35,181	44,111
Other long-term liabilities	92	168
Commitments and contingencies
Stockholders' Equity:
Common stock, $0.0001 par value; 120,000,000 shares authorized, 43,188,012 shares and 42,384,623 shares issued and outstanding, respectively	4	4
Additional paid-in capital	438,589	421,706
Accumulated deficit	(159,257)	(121,113)
Total stockholders' equity	279,336	300,597
Total Liabilities and Stockholders' Equity	$ 339,778	$ 376,235