Component of Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets:
Net operating loss carry forwards	$ 147,655	$ 127,529
Research tax credit carry forwards	21,336	18,163
Accruals and reserves	9,501	8,529
Capitalized research costs	10,662	12,757
Deferred revenue	2,486	2,180
Other	1,222	1,221
Deferred Tax Assets, Gross, Total	192,862	170,379
Less valuation allowance	(192,733)	(170,232)
Total deferred tax assets	129	147
Deferred tax liabilities:
Fixed Assets	(162)	(86)
Other	33	(61)
Total deferred tax liabilities	(129)	(147)
Net deferred tax assets