Income Taxes - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Components Of Income Tax Expense Benefit [Line Items]
Deferred income tax expense or benefit	$ 0	$ 0	$ 0
Current income tax expense or benefit	0	0	0
Approximately valuation allowance increased	11,124
Current deferred tax asset	693
Long term deferred tax liability	693
Up-front payment	35,400
Research Tax Credit Carryforward [Member]
Components Of Income Tax Expense Benefit [Line Items]
Limitations on use of net operating losses and tax credit carryforwards, percentage	50.00%
Limitations on use of net operating losses and tax credit carryforwards, period	3 years
Accrued interest or penalties related to uncertain tax positions	0	0	0
Interest or penalties Expense related to uncertain tax positions	0	0	0
Federal, state and foreign income tax returns	December 31, 2010 through December 31, 2013
U.S. [Member]
Components Of Income Tax Expense Benefit [Line Items]
Operating loss carryforwards	30,310	62,600	42,400
Operating loss carryforwards expiration year	2033	2033	2033
Tax credit carryforward amount	2,685	1,300	1,000
Credit carryforward expiration year	2032	2032	2032
State and Local Jurisdiction [Member]
Components Of Income Tax Expense Benefit [Line Items]
Operating loss carryforwards	13,287	52,300	31,300
Operating loss carryforwards expiration year	2033	2033	2033
Tax credit carryforward amount	1,443	900	400
Credit carryforward expiration year	2027	2027	2027
Foreign Tax Authority [member]
Components Of Income Tax Expense Benefit [Line Items]
Operating loss carryforwards	$ 1,977	$ 1,800	$ 1,800