Income Taxes - Deferred tax assets (liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Deferred tax assets:
Net operating loss carryforwards	$ 53,281	$ 48,535
Tax credit carryforwards	10,383	10,388
Share-based compensation	7,122	7,071
Capitalized research and development	12,370	16,440
Accruals and reserves	0	2
Total deferred tax assets	83,156	82,436
Valuation allowance	(83,156)	(82,436)
Net deferred tax assets	$ 0	$ 0