CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 83,701	$ 95,395
Available-for-sale securities	144,109	146,168
Accounts receivable, net	11,855	8,997
Inventories	11,424	13,602
Prepaid expenses and other assets	5,335	9,430
Total current assets	256,424	273,592
Property and equipment, net	884	994
Non-current assets	2,426	2,616
Total assets	259,734	277,202
Current liabilities:
Accounts payable	7,664	7,060
Accrued and other liabilities	10,300	15,891
Deferred revenue	18,223	22,142
Current portion of long-term debt	14,944	14,356
Total current liabilities	51,131	59,449
Long-term debt, net of current portion	218,782	217,034
Deferred revenue, net of current portion	7,682	6,508
Non-current accrued and other liabilities	1,243	1,296
Total liabilities	$ 278,838	$ 284,287
Commitments and contingencies
Stockholders' equity:
Preferred stock; $1.00 par value; 5,000 shares authorized; no shares issued and outstanding at March 31, 2016 and December 31, 2015
Common stock; $.001 par value; 200,000 shares authorized; 104,076 and 104,055 shares issued and outstanding at March 31, 2016 and December 31, 2015, respectively	$ 104	$ 104
Additional paid-in capital	829,680	829,428
Accumulated other comprehensive income (loss)	176	(261)
Accumulated deficit	(849,064)	(836,356)
Total stockholders' (deficit ) equity	(19,104)	(7,085)
Total liabilities and stockholders' equity	$ 259,734	$ 277,202