Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2021

Accounting Policies [Abstract]

Schedule of Restricted Cash

Restricted Cash

(in thousands)	As of September 30, 2021		As of December 31, 2020
Letter of credit security: Cambridge lease	$	—	$	264
Letter of credit security: Waltham lease	250		250
Letter of credit security: Vienna Austria lease	222		336
Letter of credit security: Boston lease	855		1,144
Total restricted cash	$	1,327	$	1,994
Restricted cash included in prepaid expenses and other current assets	$	—	$	264
Restricted cash included in other assets	$	1,327	$	1,730

Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash

The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the condensed consolidated balance sheets to the sum of the total of amounts shown in the Company’s condensed consolidated statements of cash flows as of September 30, 2021, December 31, 2020, September 30, 2020 and December 31, 2019: 

(in thousands)	September 30, 2021		December 31, 2020		September 30, 2020		December 31, 2019
Cash and cash equivalents	$	76,393	$	78,708	$	88,812	$	126,184
Restricted cash, current portion	—		264		—		—
Restricted cash, non-current	1,327		1,730		1,905		1,902
Total cash, cash equivalents and restricted cash	$	77,720	$	80,702	$	90,717	$	128,086