Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash Flows From Operating Activities:
Net loss	$ (30,527)	$ (77,417)	$ (73,553)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	848	861	462
Stock-based compensation expense	11,573	11,426	8,680
Amortization of intangible asset	454	454	121
Other	5	345	309
Changes in operating assets and liabilities:
Accounts receivable	(3,183)	(7,883)	(4,193)
Prepaid expenses and other assets	173	1,628	25
Interest receivable on investments	19	(49)	806
Inventory	(329)	(102)
Trade accounts payable	(3,428)	2,769	1,692
Accrued liabilities	(1,687)	4,312	3,452
Deferred revenue and other long-term liabilities	25,330
Net cash used in operating activities	(752)	(63,656)	(62,199)
Cash Flows From Investing Activities:
Acquisition of property and equipment	(82)	(1,016)	(1,414)
Cash paid for license			(5,800)
Purchases of investments	(30,299)	(74,974)	(18,208)
Proceeds from maturities of investments	70,281	41,980	49,500
Proceeds from sales of investments			3,894
Net cash provided by (used in) investing activities	39,900	(34,010)	27,972
Cash Flows From Financing Activities:
Proceeds from issuance of common stock associated with stock options and employee stock purchase plan	173	4,613	4,912
Proceeds from issuance of common stock, net of issuance costs		32	140,041
Other	(113)
Net cash provided by financing activities	60	4,645	144,953
Net increase (decrease) in cash and cash equivalents	39,208	(93,021)	110,726
Cash and cash equivalents, beginning of period	48,164	141,185	30,459
Cash and cash equivalents, end of period	87,372	48,164	141,185
Supplemental Schedule of Cash and Non-cash Activities:
Tax refunds received	7	78	77
Deferred revenue in accounts receivable		(669)	669
Assets recorded for which payment has not yet occurred		$ 306	$ 152