Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents, (notes 1 and 8)	$ 66,040	$ 63,961
Restricted cash	4,012	4,012
Accounts receivable	12,677	22,650
Inventory	34,928	32,752
Prepaid expenses and other current assets	9,859	7,855
Total current assets	127,516	131,230
Restricted cash	43,883	43,823
Property, plant, and equipment, net of accumulated depreciation of $28,762 and $27,970, respectively	8,948	7,255
Leased property, net of accumulated depreciation of $2,351 and $1,700, respectively	27,247	1,667
Note receivable	350	383
Goodwill	8,755	8,478
Intangible assets, net of accumulated amortization of $768 and $469, respectively	4,420	4,644
Other assets	12,284	11,976
Total assets	233,403	209,456
Current liabilities:
Accounts payable	30,566	20,455
Accrued expenses	6,725	9,852
Product warranty reserve	379	406
Accrual for loss contracts related to service	2,400	4,100
Deferred revenue	4,106	4,468
Finance obligations	5,171	2,671
Other current liabilities	368	754
Total current liabilities	49,715	42,706
Accrual for loss contracts related to service	3,020	5,950
Deferred revenue	12,445	13,997
Common stock warrant liability	2,860	5,735
Finance obligations	35,253	14,809
Long-term debt	23,907
Other liabilities	254	370
Total liabilities	127,454	83,567
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: 5,231 at June 30, 2016 and December 31, 2015	1,153	1,153
Stockholders' equity:
Common stock, $0.01 par value per share; 450,000,000 shares authorized; Issued (including shares in treasury): 180,812,358 at June 30, 2016 and 180,567,444 at December 31, 2015	1,808	1,806
Additional paid-in capital	1,123,615	1,118,917
Accumulated other comprehensive income	1,092	798
Accumulated deficit	(1,018,810)	(993,876)
Less common stock in treasury: 479,953 at June 30, 2016 and December 31, 2015	(2,909)	(2,909)
Total stockholders' equity	104,796	124,736
Total liabilities, redeemable preferred stock, and stockholders' equity	$ 233,403	$ 209,456