CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities
Net loss	$ (165,456,000)	$ (158,090,000)	$ (130,092,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	5,266,000	5,630,000	6,627,000
Amortization	809,000	937,000	967,000
Share-based compensation expense	18,240,000	20,629,000	10,414,000
Unrealized foreign exchange (gains)/losses	(2,438,000)	540,000	(1,333,000)
Amortization on available-for-sale debt securities	2,525,000	5,276,000	3,836,000
Other	816,000	1,173,000	(55,000)
Changes in operating assets and liabilities:
(Increase)/decrease in receivables and other operating assets	(9,813,000)	(19,358,000)	1,747,000
Decrease in non-current operating assets			2,458,000
Increase in payables and other current liabilities	4,408,000	4,207,000	3,867,000
Increase in deferred revenue	3,874,000	149,785,000	47,973,000
Net cash (used in)/provided by operating activities	(141,769,000)	10,729,000	(53,591,000)
Cash flows from investing activities
Acquisition of property, plant and equipment	(29,496,000)	(8,574,000)	(2,341,000)
Acquisition of intangibles assets	(244,000)	(207,000)	(565,000)
Maturity or redemption of marketable securities	166,994,000	224,343,000	105,022,000
Investment in marketable securities	(48,117,000)	(139,762,000)	(381,040,000)
Net cash provided by/(used in) investing activities	89,137,000	75,800,000	(278,924,000)
Cash flows from financing activities
Proceeds from issuance of common stock from offerings, net of commissions and issuance costs	12,817,000	2,529,000	334,388,000
Proceeds from exercise of stock options	50,000	759,000	5,663,000
Net cash provided by financing activities	12,867,000	3,288,000	340,051,000
Effect of currency exchange rate changes on cash, cash equivalents and restricted cash	(2,299,000)	365,000	(960,000)
Net (decrease)/increase in cash, cash equivalents and restricted cash	(42,064,000)	90,182,000	6,576,000
Cash, cash equivalents and restricted cash at start of period	151,666,000	61,484,000	54,908,000
Cash, cash equivalents and restricted cash at end of period	109,602,000	151,666,000	61,484,000
Supplemental cash flow information
Interest received	5,149,000	7,765,000	6,216,000
Amortization on available-for-sale debt securities	2,525,000	5,276,000	3,836,000
Income taxes paid	$ 630,000	$ 535,000	$ 75,000