Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jan. 02, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 04, 2021	Jan. 01, 2018	Dec. 31, 2017
Summary Of Significant Accounting Policies [Line Items]
Stock based compensation expenses		$ 6,829	$ 6,341	$ 7,534
Weighted average fair value of stock option granted		$ 2.15	$ 2.47	$ 1.64
Accumulated deficit		$ (764,101)	$ (684,125)				$ (712,442)
Transaction Price		57,500
Changes in contract liability				$ (146)
Strategic advisory services fee		$ 1,000
Office and computer equipment
Summary Of Significant Accounting Policies [Line Items]
Property and equipment useful life		3 years
Software
Summary Of Significant Accounting Policies [Line Items]
Property and equipment useful life		3 years
Laboratory equipment
Summary Of Significant Accounting Policies [Line Items]
Property and equipment useful life		5 years
Leasehold improvements
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life		Life of the lease
Difference between revenue guidance in effect before and after topic 606
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit						$ 8,100
Research and Development Services Contract Term		9 years
Changes in contract liability	$ 8,100
Stock Options
Summary Of Significant Accounting Policies [Line Items]
Stock based compensation expenses		$ 4,300	4,000	3,000
Restricted Stock
Summary Of Significant Accounting Policies [Line Items]
Stock based compensation expenses		2,500	2,300	4,500
Restricted Stock Units (RSUs) [Member]
Summary Of Significant Accounting Policies [Line Items]
Stock based compensation expenses		6,800	6,300	7,500
Accrued Expenses [Member]
Summary Of Significant Accounting Policies [Line Items]
Cost Incurred in appointment of directors		$ 0
Subsequent Event
Summary Of Significant Accounting Policies [Line Items]
Reimbursement of expenses due					$ 400
ASU 2014-09
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit							(720,573)
ASU 2014-09 | Difference between revenue guidance in effect before and after topic 606
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit							$ (8,131)
Changes in contract liability			$ 0	$ 0