Income Taxes - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Aug. 31, 2004	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Provision for income taxes		$ 0	$ 240,000
Valuation allowance of deferred tax asset		670,617,000	665,365,000
Change in the valuation allowance		5,252,000	11,067,000
Federal operating loss carryforwards		2,100,000,000
State operating loss carryforwards		1,300,000,000
Federal operation loss carryforwards, not subject to expiration		$ 117,800,000
Operating loss carryforwards, limitations on use		Pursuant to Internal Revenue Code (“IRC”) Sections 382 and 383, annual use of the Company’s federal and state net operating loss and research and development credit carryforwards may be limited in the event a cumulative change in ownership of more than 50% occurs within a three-year period.
Net operating loss carryforwards	$ 216,000,000
Net operating loss and credit carryforwards, annual use limitation	$ 13,000,000
Research and development credits		$ 80,488,000	81,583,000
Research and development credits begin to expire		2020
Undistributed earnings from its foreign subsidiaries		$ 0
Adjustment of deferred tax liability due to adoption of new leases guidance		958,000
Adjustment of deferred tax asset due to adoption of new leases guidance		671,575,000	$ 665,365,000
(“ASC”) Topic 842 – Leases
Income Taxes [Line Items]
Adjustment of deferred tax liability due to adoption of new leases guidance		700,000
Adjustment of deferred tax asset due to adoption of new leases guidance		700,000
Federal
Income Taxes [Line Items]
Research and development credits		$ 54,200,000
Research and development credits begin to expire		2024
New Jersey
Income Taxes [Line Items]
Research and development credits begin to expire		2020
Connecticut
Income Taxes [Line Items]
Research and development credits		$ 900,000
Research and development credits not expire		15,700,000
State
Income Taxes [Line Items]
Research and development credits		$ 26,300,000