Significant Components of Deferred Tax Assets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets:
Federal and state net operating loss carryforwards	$ 102,478	$ 74,390
Federal and state research tax credit carryforwards	10,750	7,551
Deferred revenue	1,755	1,434
Stock options	2,895	2,362
Capitalized acquisition costs	1,295	1,503
Other	654	1,859
Total deferred tax assets	119,827	89,099
Valuation allowance	(119,827)	(89,099)
Net deferred tax assets