Summary of Significant Accounting Policies - Leases (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) lease
Basis Of Presentation [Line Items]
Lease, Practical Expedient, Use of Hindsight [true false]	true
Lease, Practical Expedients, Package [true false]	true
Stamford Operating Lease [Member]
Basis Of Presentation [Line Items]
Annual incremental borrowing rate	7.00%
Operating lease, renewable term	5 years
Stamford Operating Lease [Member] | ASC 842 [Member]
Basis Of Presentation [Line Items]
Number of operating lease | lease	1
Annual incremental borrowing rate	7.00%
Operating lease, renewable term	5 years
Cumulative effect adjustment | $	$ 0