CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 37,619	$ 63,474
Short-term investments	162,833	148,703
Accounts receivable, net	6,278	5,932
Inventories	14,255	15,206
Receivable from collaboration	370	428
Prepaid and other current assets	5,740	6,288
Total current assets	227,095	240,031
Property, plant and equipment, net	8,702	9,206
Long-term investments	17,409	17,527
Restricted cash	460	460
Total assets	253,666	267,224
Current liabilities:
Accounts payable	3,398	3,732
Accrued expenses	27,986	28,916
Deferred revenues	6,346	6,346
Total current liabilities	37,730	38,994
Long-term liabilities:
Deferred revenues	43,672	45,196
Other long-term liabilities	2,341	2,438
Total liabilities	83,743	86,628
Commitments and contingencies (Notes I & J)
Stockholders' equity:
Preferred stock, par value $0.01 per share, 2,000,000 shares authorized; none issued
Common stock, par value $0.01 per share, 58,750,000 shares authorized; 21,358,395 and 21,306,413 shares issued and outstanding at March 31, 2012 and December 31, 2011, respectively	213	213
Additional paid-in capital	626,799	625,133
Accumulated other comprehensive loss	(4,765)	(4,842)
Accumulated deficit	(452,324)	(439,908)
Total stockholders' equity	169,923	180,596
Total liabilities and stockholders' equity	$ 253,666	$ 267,224