Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 43,138	$ 20,018
Short-term investments	4,005	9,028
Accounts receivable, net	6,215	7,507
Inventory	3,069	4,085
Other current assets	2,078	2,159
Total current assets	58,505	42,797
Fixed assets, net	5,139	5,329
Restricted cash	1,100	1,100
Other assets	5,895	6,260
Total assets	70,639	55,486
Current liabilities:
Accounts payable and accrued expenses	11,686	12,472
Current portion of deferred revenue	3,683	5,449
Current portion of long-term obligations	465	445
Other current liabilities	1,715
Total current liabilities	17,549	18,366
Deferred revenue	6,787	6,402
Notes payable	81,354	78,061
Long-term obligations	579	931
Deferred rent and other long-term liabilities	3,172	3,286
Total liabilities	109,441	107,046
Commitments and contingencies
Stockholders' deficit:
Preferred stock, $0.01 par value; 1,000,000 shares authorized; 41,418 and 0 shares issued and outstanding at September 30, 2013 and December 31, 2012, respectively
Common stock, $0.01 par value; 200,000,000 shares authorized; 110,347,285 and 98,798,065 shares issued and outstanding at September 30, 2013 and December 31, 2012, respectively	1,103	995
Additional paid-in capital	492,091	453,625
Accumulated deficit	(531,999)	(506,186)
Accumulated other comprehensive income	3	6
Total stockholders' deficit	(38,802)	(51,560)
Total liabilities and stockholders' deficit	$ 70,639	$ 55,486