Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
Summary Of Net Deferred Tax Assets [Line Items]
Valuation allowance against net deferred tax assets		$ 23,900,000	$ 23,900,000
Provision for Income taxes	85,000	85,000
Percentage of ownership change, limitations on utilization of net operating loss (NOL) and research and development (R&D) credit carryforwards		50.00%
Ownership change test period, limitations on utilization of net operating loss (NOL) and research and development (R&D) credit carryforwards		3 years
Net federal operating loss		53,000,000
Future annual deductibility of company's total net operating loss carryforwards		$ 2,500,000
Description of net operating losses		The Company believes limitations exist only on the future annual deductibility of approximately $2.5 million of the Company's total net operating loss carryforwards