Restructuring - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	1 Months Ended	12 Months Ended
	Nov. 30, 2012 Position	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011 Position
Restructuring Cost and Reserve [Line Items]
Reduction in workforce				28.00%
Reduction in workforce, number of employees	21			35
Restructuring charges included severance and related costs		$ 764	$ 185	$ 1,145
Research and development
Restructuring Cost and Reserve [Line Items]
Restructuring charges included severance and related costs		400	100	500
General and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring charges included severance and related costs		$ 400	$ 100	$ 600