Income Taxes - Operating loss carryforwards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Taxes
Tax expense	$ 0	$ 0
Increase in valuation allowance	22,000
Federal
Income Taxes
Operating loss carryforwards	209,300
Operating loss carryovers not subject to expiration	204,500
State
Income Taxes
Operating loss carryforwards	$ 180,900