Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 314,460	$ 230,146
Accounts receivable	1,056	679
Inventories	5,992	1,106
Other current assets	4,208	4,560
Total current assets	325,716	236,491
Intangible assets, net	14,268	14,732
Property and equipment, net	2,690	2,779
Restricted cash	500	500
Other assets	803	779
Total assets	343,977	255,281
Current liabilities:
Accounts payable	12,334	8,019
Accrued expenses	40,133	36,628
Deferred revenue, current	3,362	500
Other current liabilities	3,043	1,534
Total current liabilities	58,872	46,681
Convertible notes, net	123,797	121,325
Deferred revenue, non-current	163	288
Other non-current liabilities	181	113
Total liabilities	$ 183,013	$ 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 March 31, 2016; no shares issued or outstanding at both December 31, 2015 and March 31, 2016
Common stock, $0.0001 par value; 100,000,000 shares authorized at both December 31, 2015 and March 31, 2016; 40,279,783 and 44,714,130 shares issued and outstanding at December 31, 2015 and March 31, 2016, respectively	$ 4	$ 4
Additional paid-in capital	853,744	688,788
Accumulated other comprehensive loss	(99)
Accumulated deficit	(692,685)	(601,918)
Total stockholders' equity	160,964	86,874
Total liabilities and stockholders' equity	$ 343,977	$ 255,281