Income Taxes (Schedule Of Company's Deferred Tax Assets) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Line Items]
Deferred revenue	$ 15,491	$ 54,116
Net operating loss carry forward	72,232	30,767
Stock-based compensation	12,721	9,872
Research and development credits	13,897	11,280
Depreciation, amortization and other	109	133
Accruals and reserves	6,530	552
Total deferred tax assets	120,980	106,720
Less: valuation allowance	(98,671)	(106,720)
Total net deferred tax assets	22,309
Convertible Notes	(22,309)
Total deferred tax liabilities	(22,309)
Net deferred tax assets
Net current deferred tax assets (included in "Prepaid expenses and other current assets")	3,800
Net non-current deferred tax assets
Net current deferred tax liabilities
Net non-current deferred tax liabilities (included in "Other non-current liabilities")	(3,800)
Net deferred tax assets