CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 154,137	$ 95,395
Available-for-sale securities	129,449	146,168
Accounts receivable, net	10,295	8,997
Inventories	11,259	13,602
Prepaid expenses and other assets	5,552	9,430
Total current assets	310,692	273,592
Property and equipment, net	715	994
Non-current assets	1,744	2,616
Total assets	313,151	277,202
Current liabilities:
Accounts payable	6,440	7,060
Accrued and other liabilities	9,944	15,891
Deferred revenue	89,128	22,142
Current portion of long-term debt	9,015	14,356
Total current liabilities	114,527	59,449
Long-term debt, net of current portion	229,876	217,034
Deferred revenue, net of current portion	6,845	6,508
Non-current accrued and other liabilities	16	1,296
Total liabilities	351,264	284,287
Commitments and contingencies
Stockholders' deficit
Preferred stock; $1.00 par value; 5,000 shares authorized; no shares issued and outstanding at September 30, 2016 and December 31, 2015
Common stock; $.001 par value; 200,000 shares authorized; 104,819 and 104,055 shares issued and outstanding at September 30, 2016 and December 31, 2015, respectively	105	104
Additional paid-in capital	831,192	829,428
Accumulated other comprehensive income (loss)	207	(261)
Accumulated deficit	(869,617)	(836,356)
Total stockholders' deficit	(38,113)	(7,085)
Total liabilities and stockholders' deficit	$ 313,151	$ 277,202