Condensed Statements of Cash Flows (Unaudited) (USD $)	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Operating activities
Net loss	$ (43,662,000)	$ (43,586,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	826,000	822,000
Loss (gain) on disposal of assets	1,000	(1,000)
Inventory write-down	224,000
Stock-based compensation	4,752,000	4,570,000
Non-cash interest expense	14,000	35,000
Amortization of intangible assets	672,000	896,000
Amortization of discount on note payable	272,000	388,000
Amortization of premiums on available-for-sale securities, net of accretion of discounts	(13,000)	22,000
Changes in operating assets and liabilities:
Accounts receivable	(2,265,000)	(1,136,000)
Inventory	(3,164,000)	(6,241,000)
Prepaid expenses and other current assets	81,000	356,000
Accounts payable	4,442,000	2,108,000
Deferred revenue	386,000	677,000
Accrued liabilities and other liabilities	2,087,000	1,445,000
Net cash used in operating activities	(35,347,000)	(39,645,000)
Investing activities
Purchases of marketable securities		(36,826,000)
Maturities and sales of marketable securities	40,850,000	26,358,000
Restricted cash		(300,000)
Purchases of property and equipment	(1,222,000)	(1,422,000)
Proceeds from the sale of property and equipment	1,000	1,000
Net cash provided by (used in) investing activities	39,629,000	(12,189,000)
Financing activities
Proceeds from issuance of common stock, net	96,000	1,401,000
Net cash provided by financing activities	96,000	1,401,000
Net increase (decrease) in cash and cash equivalents	4,378,000	(50,433,000)
Cash and cash equivalents at beginning of period	82,609,000	112,175,000
Cash and cash equivalents at end of period	86,987,000	61,742,000
Supplemental disclosures
Property and equipment purchases in accounts payable and accrued expenses	224,000	887,000
Unrealized loss on investment securities	(2,000)
Cash paid for interest and fees	$ 1,465,000	$ 1,637,000