Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 320,204	$ 230,146
Accounts receivable	510	679
Inventories	8,381	1,106
Other current assets	8,722	4,560
Total current assets	337,817	236,491
Intangible assets, net	13,805	14,732
Property and equipment, net	2,718	2,779
Restricted cash	500	500
Other assets	1,097	779
Total assets	355,937	255,281
Current liabilities:
Accounts payable	13,992	8,019
Accrued expenses	42,836	36,628
Deferred revenue, current	1,662	500
Other current liabilities	1,534	1,534
Total current liabilities	60,024	46,681
Convertible notes, net	126,407	121,325
Deferred revenue, non-current	38	288
Other non-current liabilities	163	113
Total liabilities	186,632	168,407
Commitments and contingencies (Note 10)
Stockholders' equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized at both December 31, 2015 and June 30, 2016; no shares issued or outstanding at both December 31, 2015 and June 30, 2016
Common stock, $0.0001 par value; 100,000,000 shares authorized at both December 31, 2015 and June 30, 2016; 40,279,783 and 46,012,660 shares issued and outstanding at December 31, 2015 and June 30, 2016, respectively	5	4
Additional paid-in capital	921,971	688,788
Accumulated other comprehensive loss	(98)
Accumulated deficit	(752,573)	(601,918)
Total stockholders' equity	169,305	86,874
Total liabilities and stockholders' equity	$ 355,937	$ 255,281