Restructuring - Additional Information (Detail) (USD $)	12 Months Ended		0 Months Ended	12 Months Ended	0 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Aug. 30, 2013 sqft	Dec. 31, 2014	Oct. 17, 2013 sqft
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 1,700,000
Loss on disposition of business	800,000
Loss on disposal of fixed assets	600,000
Loss on disposal of fixed assets	(585,000)	(48,000)
Severance and Health Benefit Continuation Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1,300,000
Boston, MA
Restructuring Cost and Reserve [Line Items]
Area under sublease agreement			5,249
Loss on sublease	42,000
Remaining contractual obligation	367,000
Sublease revenue from subtenant	325,000
Loss on disposal of fixed assets	(194,000)
Security deposit	20,000	127,000		127,000
Date of sublease vacated for lease				2014-10
Amount applied for deposit				20,000
New York, NY
Restructuring Cost and Reserve [Line Items]
Area under sublease agreement					7,259
Loss on sublease	729,000
Remaining contractual obligation	2,300,000
Sublease revenue from subtenant	1,600,000
Loss on disposal of fixed assets	(392,000)
General and Administrative Expense
Restructuring Cost and Reserve [Line Items]
Restructuring charges	600,000
Research and Development Expense
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 1,100,000