Restructuring - Additional Information (Detail) (USD $)	3 Months Ended				0 Months Ended	12 Months Ended	0 Months Ended	12 Months Ended
	Jun. 30, 2013	Apr. 03, 2013 Position	Apr. 03, 2013 Filled positions Position	Apr. 03, 2013 Unfilled positions Position	Aug. 30, 2013 Boston, MA sqft	Dec. 31, 2013 Boston, MA	Oct. 17, 2013 New York, NY sqft	Dec. 31, 2013 New York, NY	Jun. 30, 2014 New York, NY	Dec. 31, 2012 New York, NY	Dec. 31, 2011 New York, NY
Restructuring Cost and Reserve [Line Items]
Total charges incurred related to workforce reduction	$ 1,700,000
Number of positions eliminated		65	40	25
Area under sublease agreement					5,249		7,259
Loss on sublease						42,000		729,000
Remaining contractual obligation						367,000		2,300,000
Sublease revenue from subtenant						325,000		1,600,000
Loss on disposal of fixed assets						(194,000)		(392,000)
Letter of credit									$ 388,000	$ 388,000	$ 388,000