Income Taxes - Loss carryforwards (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Federal
Tax Credit Carryforward
Operating loss carryforwards	$ 51,600,000	$ 41,500,000
Operating loss carryforwards not subject to expiration	51,600,000
Tax credits subject to expiration	17,300,000
State
Tax Credit Carryforward
Capital loss carryforwards	1,400,000	1,000,000.0
Operating loss carryforwards	197,300,000	147,300,000
Operating loss carryforwards subject to expiration	197,300,000
Tax credits subject to expiration	1,400,000
Capital Loss Carryforward | Federal
Tax Credit Carryforward
Capital loss carryforwards	$ 21,700,000	$ 22,700,000