Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities
Net loss	$ (122,245)	$ (149,910)
Adjustments to reconcile net loss to net cash used in operating activities:
Amortization of right-of-use assets	2,352	1,869
Depreciation of property and equipment	7,483	8,114
Share-based compensation expense	16,407	14,296
Changes in operating assets and liabilities:
Accounts receivable	30,000	20,000
Prepaid expenses	3,850	(808)
Other assets	(338)	14,121
Accounts payable	(6,567)	5,117
Accrued expenses and other current liabilities	2,890	(4,214)
Deferred revenue	(18,464)	(20,077)
Operating lease liabilities	(3,887)	(3,243)
Other non-current liabilities	(474)	(1,247)
Net cash used in operating activities	(88,993)	(115,982)
Cash flows from investing activities
Purchases of property and equipment	(560)	(1,338)
Net cash used in investing activities	(560)	(1,338)
Cash flows from financing activities
Proceeds from issuance of ordinary shares, net of offering costs		93,744
Proceeds from the exercise of share options	250	741
Proceeds from the ESPP	608	171
Net cash provided by financing activities	55,828	154,538
Effect of foreign exchange rates on cash	(208)	122
Net increase (decrease) in cash, cash equivalents and restricted cash	(33,933)	37,340
Cash, cash equivalents and restricted cash, beginning of period	188,148	150,808
Cash, cash equivalents and restricted cash, end of period	154,215	188,148
Supplemental disclosure of cash flow information:
Increase in operating lease right-of-use assets and lease liabilities related to new lease	4,498
At-The-Market Equity Program [Member]​
Cash flows from financing activities
Proceeds from issuance of ordinary shares, net of offering costs	$ 54,970	$ 59,882