CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash flows from operating activities:
Net loss	$ (13,064)	$ (58,488)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	2,742	1,966
Impairment loss on assets held for sale	800
Non-cash equity-based compensation expense	5,312	8,798
Non-cash income tax benefit	(793)	(611)
Amortization of premium/discount on purchased securities	2,181	2,778
Gains (losses) on investments, net	1,469	194
Changes in operating assets and liabilities:
Accounts receivable, net	(1,431)	(1,284)
Inventories	3,860	2,094
Receivable from collaboration	(349)	249
Prepaid and other current assets	(1,339)	2,163
Accounts payable and accrued expenses	(13,386)	5,083
Deferred revenues	(3,668)	(4,829)
Other long-term liabilities	(302)	(260)
Total adjustments	(4,904)	16,341
Net cash used in operating activities	(17,968)	(42,147)
Cash flows from investing activities:
Proceeds from sales or maturities of investments	102,540	99,096
Purchase of investments	(105,305)	(93,707)
Capital expenditures	(47)	(415)
Net cash (used in) provided by investing activities	(2,812)	4,974
Cash flows from financing activities:
Proceeds from the exercise of stock options	56	10
Proceeds from the issuance of common stock under ESPP	150	294
Net cash provided by financing activities	206	304
Net decrease in cash and cash equivalents	(20,574)	(36,869)
Cash and cash equivalents at beginning of the period	63,474	112,646
Cash and cash equivalents at end of the period	$ 42,900	$ 75,777