CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net loss	$ (3,895)	$ (12,416)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	650	551
Amortization of premium/discount on purchased securities	681	766
Non-cash equity-based compensation expense	2,283	1,685
(Gains) on sale of assets held for sale	(299)
(Gains) on investments, net	(6)
Changes in operating assets and liabilities:
Accounts receivable, net	(2,109)	(346)
Inventories	1,834	2,131
Receivable from collaboration	155	58
Prepaid and other current assets	(6)	548
Accounts payable and accrued expenses	(7,074)	(2,463)
Deferred revenues	(1,816)	(1,524)
Other long-term liabilities	(111)	(97)
Total adjustments	(5,818)	1,309
Net cash used in operating activities	(9,713)	(11,107)
Cash flows from investing activities:
Proceeds from sales or maturities of investments	30,663	37,504
Purchase of investments	(33,906)	(52,205)
Capital expenditures	(23)	(47)
Proceeds from sale of assets held for sale	368
Net cash used in investing activities	(2,898)	(14,748)
Cash flows from financing activities:
Proceeds from the exercise of stock options	163
Net cash provided by financing activities	163
Net decrease in cash and cash equivalents	(12,448)	(25,855)
Cash and cash equivalents at beginning of the period	46,293	63,474
Cash and cash equivalents at end of the period	$ 33,845	$ 37,619