Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013 Audit	Dec. 31, 2012	Dec. 31, 2011 Ownership
Income Taxes Disclosure [Line Items]
Accrued amount for interest and penalties related to the non-payment of U.S. federal income taxes	$ 600,000	$ 600,000	$ 300,000
Expiration date of carryforwards	Through 2033
Percentage of increase the ownership	5.00%
Aggregate period	3 years
Number of ownership change			2
Amount of valuation allowance on deferred tax assets	46,549,000	31,786,000	10,700,000
Increase in valuation allowance	14,800,000
Unrecognized tax benefits	0	0
Number of federal or state audit in process	0
Minimum [Member]
Income Taxes Disclosure [Line Items]
Shareholders in the stock of a corporation	50.00%
Federal Income Tax [Member]
Income Taxes Disclosure [Line Items]
Net operating loss	49,200,000
Federal Income Tax [Member] | Research Tax Credit Carryforward [Member]
Income Taxes Disclosure [Line Items]
Research and development tax credit	627,000
State Income Tax [Member]
Income Taxes Disclosure [Line Items]
Net operating loss	90,300,000
State Income Tax [Member] | Research Tax Credit Carryforward [Member]
Income Taxes Disclosure [Line Items]
Research and development tax credit	17,000
State and Local Jurisdiction [Member]
Income Taxes Disclosure [Line Items]
Net operating loss	$ 182,000