Restructuring Charge - Additional Information (Detail) (USD $)	1 Months Ended			12 Months Ended	14 Months Ended
	Apr. 30, 2013 Employee	Jan. 31, 2013 Employee	Nov. 30, 2012 Employee	Dec. 31, 2013 Employee	Dec. 31, 2013	Dec. 31, 2012
Restructuring Cost And Reserve [Line Items]
Number of employees terminated	2	5	16	23
Net restructuring charge				$ 79,000	$ 698,000
Payment of Severance cost				223,000
Accrued restructuring liability				0	0	143,000
Research and Development Expense
Restructuring Cost And Reserve [Line Items]
Net restructuring charge				66,000
General and Administrative Expense
Restructuring Cost And Reserve [Line Items]
Net restructuring charge				$ 13,000