Income Taxes (Schedule Of Deferred Tax Assets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Abstract]
Net operating loss carryforwards	$ 122,656	$ 73,788
Deferred revenue	48,062	41,547
Capitalized research and development	21,226	26,443
Tax credit carryforwards	31,365	26,365
Share-based compensation	10,730	7,318
Depreciation and amortization	2,210	1,931
Other	8,242	5,466
Total deferred tax assets	244,491	182,858
Less: valuation allowance	(244,491)	(182,858)
Net deferred tax assets	$ 0	$ 0