Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 15,035	$ 24,828
Restricted cash	13,367	13,898
Accounts receivable	31,509	15,331
Inventory	42,288	48,776
Prepaid expenses and other current assets	15,661	16,774
Total current assets	117,860	119,607
Restricted cash	27,020	29,329
Property, plant, and equipment, net of accumulated depreciation of $32,801 and $31,588, respectively	11,544	10,414
Leased property, net of accumulated depreciation of $16,394 and $11,812, respectively	95,621	87,065
Goodwill	9,210	9,445
Intangible assets, net of accumulated amortization of $2,036 and $1,735, respectively	4,250	3,785
Other assets	10,722	11,165
Total assets	276,227	270,810
Current liabilities:
Accounts payable	36,128	42,362
Accrued expenses	10,777	10,595
Deferred revenue	10,410	8,630
Finance obligations	40,581	34,506
Current portion of long-term debt	11,461	18,762
Other current liabilities	309	866
Total current liabilities	109,666	115,721
Deferred revenue	28,130	25,809
Common stock warrant liability	2,799	4,391
Finance obligations	33,693	37,069
Convertible senior notes, net	59,812
Long-term debt	15,272	13,371
Other liabilities	18	94
Total liabilities	249,390	196,455
Stockholders' equity:
Common stock, $0.01 par value per share; 750,000,000 shares authorized; Issued (including shares in treasury): 229,655,825 at June 30, 2018 and 229,073,517 at December 31, 2017	2,297	2,291
Additional paid-in capital	1,276,989	1,250,899
Accumulated other comprehensive income	1,844	2,194
Accumulated deficit	(1,224,365)	(1,178,636)
Less common stock in treasury: 15,002,663 at June 30, 2018 and 587,151 at December 31, 2017	(30,637)	(3,102)
Total stockholders' equity	26,128	73,646
Total liabilities, redeemable preferred stock, and stockholders' equity	276,227	270,810
Series C Redeemable Convertible Preferred Stock
Redeemable preferred stock
Series C redeemable convertible preferred stock, $0.01 par value per share (aggregate involuntary liquidation preference $16,664); 10,431 shares authorized; Issued and outstanding: 2,620 at June 30, 2018 and December 31, 2017	$ 709	$ 709