Restricted Cash - Additional Information (Detail) - USD ($) $ in Thousands		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash in current assets	$ 700	$ 700	$ 700
Restricted cash balance	769	769	769
Shelton Lease [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash in current assets	700	$ 700	700
Operating lease, expiration date		Oct. 13, 2017
Stamford Lease [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Letter of credit, remaining amount	769	$ 769
Letter of credit, remaining amount after three years	$ 408	408
Lease term	2023-10
Restricted cash balance	$ 769	$ 769	$ 769