Leases (Tables)

12 Months Ended

Dec. 31, 2021

Leases [Abstract]

Components of Operating Lease Costs

The components of operating lease costs were as follows (in thousands):

	FOR THE YEAR ENDED DECEMBER 31,
	2021			2020
Operating lease costs	$	4,882		$	4,836
Short-term lease costs		27			19
Variable lease costs		2,582			2,222
Sublease income		(1,850	)		(861	)
	$	5,641		$	6,216

Summary of Additional Lease Information

Additional lease information is summarized in the following table (in millions, except lease term and discount rate):

	FOR THE YEAR ENDED DECEMBER 31,
	2021			2020
Cash paid for amounts included in the measurement of operating    lease liabilities	$	6.0		$	6.0
Weighted-average remaining lease term - operating leases (years)		7.9			8.9
Weighted-average discount rate - operating leases		10.1	%		10.3	%

Schedule of Undiscounted Cash Flows Used in Calculating the Operating Lease Liabilities and Amounts to be Received under the Sublease

Undiscounted cash flows used in calculating the Company’s operating lease liabilities and amounts to be received under the sublease at 35 CambridgePark Drive and 4 Hartwell Place as of December 31, 2021 are as follows (in thousands):

Fiscal Year	OPERATING LEASE PAYMENTS			SUBLEASE   RECEIPTS		NET OPERATING LEASE PAYMENTS
2022	$	6,252		$	2,821	$	3,431
2023		6,436			1,962		4,474
2024		6,625			936		5,689
2025		6,820					6,820
2026		7,020					7,020
Thereafter		21,779					21,779
Total undiscounted cash flows	$	54,932		$	5,719	$	49,213
Less: Amounts representing interest		(17,387	)
Present value of lease liabilities	$	37,545