Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax [Line Items]
Increase (Decrease) in valuation allowance	$ 30,700,000	$ (6,800,000)
Unrecognized income tax benefits that, if recognized, would affect effective tax rate	365,000	365,000
Unrecognized income tax benefits	2,048,000	1,435,000	1,344,000	973,000
Minimum
Income Tax [Line Items]
Tax years remain open to examinations	2003
Maximum
Income Tax [Line Items]
Tax years remain open to examinations	2013
Federal
Income Tax [Line Items]
Net operating loss carryforwards	260,000,000
Federal | Research Tax Credit Carryforward
Income Tax [Line Items]
Tax credits carryforwards	10,900,000
Federal | Research Tax Credit Carryforward | Minimum
Income Tax [Line Items]
Federal research tax credits, expiration year	2023
Federal | Research Tax Credit Carryforward | Maximum
Income Tax [Line Items]
Federal research tax credits, expiration year	2033
State
Income Tax [Line Items]
Net operating loss carryforwards	227,600,000
State | Minimum
Income Tax [Line Items]
Net operating loss carryforwards, expiration year	2014
State | Maximum
Income Tax [Line Items]
Net operating loss carryforwards, expiration year	2033
State | Research Tax Credit Carryforward
Income Tax [Line Items]
Tax credits carryforwards	$ 2,400,000