Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 62,522	$ 67,005
Restricted cash		158
Short-term investments	99,970
Accounts receivable, net	6,305	4,218
Inventory	7,482	4,973
Prepaid expenses and other current assets	3,624	3,122
Total current assets	179,903	79,476
Property and equipment, net	28,139	25,867
Long-term investments	38,950
Other assets	5,799	3,265
Total assets	252,791	108,608
Current liabilities:
Accounts payable	7,486	5,582
Accrued expenses and other current liabilities	22,406	19,707
PPP loan — current	4,873	4,061
Deferred revenue — current	20,126	33,275
Recognized loss on purchase commitments — current	5,538	11,080
Total current liabilities	60,429	73,705
Senior convertible notes	223,217
MidCap credit facility	38,614	49,335
Mann Group promissory notes	18,425	63,027
Accrued interest — Mann Group promissory notes	169	4,150
PPP loan — long term		812
2024 convertible notes		5,000
Recognized loss on purchase commitments — long term	83,179	84,208
Operating lease liability	564	1,202
Deferred revenue — long term	1,589	1,662
Milestone rights liability	4,839	5,926
Deposits from customer	5,317
Total liabilities	436,342	289,027
Commitments and contingencies (Note 12)
Stockholders' deficit:
Undesignated preferred stock, $0.01 par value — 10,000,000 shares authorized; no shares issued or outstanding as of June 30, 2021 and December 31, 2020
Common stock, $0.01 par value - 400,000,000 shares authorized, 249,617,550 and 242,117,089 shares issued and outstanding at June 30, 2021 and December 31, 2020, respectively	2,496	2,421
Additional paid-in capital	2,911,535	2,866,303
Accumulated deficit	(3,097,582)	(3,049,143)
Total stockholders' deficit	(183,551)	(180,419)
Total liabilities and stockholders' deficit	$ 252,791	$ 108,608