Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 230,146	$ 256,861
Accounts receivable	679
Inventories	1,106
Other current assets	4,560	1,735
Total current assets	236,491	258,596
Intangible assets, net	14,732
Property and equipment, net	2,779	1,022
Restricted cash	500
Other assets	779	767
Total assets	255,281	260,385
Current liabilities:
Accounts payable	8,019	6,089
Accrued expenses	36,628	16,750
Deferred revenue, current	500
Other current liabilities	1,534	1,526
Total current liabilities	46,681	24,365
Convertible notes, net	121,325	111,964
Deferred revenue, non-current	288
Other non-current liabilities	113
Total liabilities	$ 168,407	$ 136,329
Commitments and contingencies (Notes 6 and 12)
Stockholders' equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized at both December 31, 2014 and December 31, 2015; no shares issued or outstanding at both December 31, 2014 and December 31, 2015
Common stock, $0.0001 par value; 100,000,000 shares authorized at both December 31, 2014 and December 31, 2015; 36,110,082 and 40,279,783 shares issued and outstanding at December 31, 2014 and December 31, 2015, respectively	$ 4	$ 4
Additional paid-in capital	688,788	474,562
Accumulated deficit	(601,918)	(350,510)
Total stockholders' equity	86,874	124,056
Total liabilities and stockholders' equity	$ 255,281	$ 260,385