Discontinued operations - Significant Non-Cash Items and Capital Expenditures (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating activities:
Change in fair value of contingent consideration	$ 0	$ 416
Stock-based compensation expense	21,298	73,687
Investing activities:
Purchase of property, plant and equipment	(6,836)	(9,204)
Purchase of intangible assets	0	(2,000)
Supplemental cash flow disclosures:
Purchases of property, plant and equipment included in accounts payable and accrued expenses	$ 842	1,508
Discontinued Operations, Disposed of by Means Other than Sale, Spinoff | 2seventy bio
Operating activities:
Change in fair value of contingent consideration		416
Depreciation and amortization		8,300
Stock-based compensation expense		19,104
Loss on fixed assets disposal		254
Investing activities:
Purchase of property, plant and equipment		(7,675)
Purchase of intangible assets		(2,000)
Supplemental cash flow disclosures:
Purchases of property, plant and equipment included in accounts payable and accrued expenses		1,345
Purchases of intangible assets included in accounts payable and accrued expenses, net of reimbursement receivable from collaboration partner		$ 6,500