Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Line Items]
Income tax provision
Statutory income tax rate	34.00%
Net valuation allowance increased	12,600,000	13,700,000	10,300,000
Unrecognized tax positions	0	0
Domestic tax authority [Member]
Income Taxes [Line Items]
Net operating loss carry-forwards	326,200,000
Research and development tax credit carry-forwards	7,500,000
Net operating loss carry-forwards expiration	Expire at various dates beginning in 2018
State and local jurisdiction [Member]
Income Taxes [Line Items]
Net operating loss carry-forwards	209,500,000
Research and development tax credit carry-forwards	$ 6,800,000
Net operating loss carry-forwards expiration	Begin to expire in 2014