Income Taxes - Income taxes paid (net of refunds received) (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Tax Paid, by Individual Jurisdiction [Line Items]
Income taxes paid (net of refunds received)	$ 191,000	$ 694,000	$ 88,000
Virginia
Income Tax Paid, by Individual Jurisdiction [Line Items]
Income taxes paid (net of refunds received)	105,000
Other states
Income Tax Paid, by Individual Jurisdiction [Line Items]
Income taxes paid (net of refunds received)	6,000
Foreign - Netherlands
Income Tax Paid, by Individual Jurisdiction [Line Items]
Income taxes paid (net of refunds received)	137,000
Foreign - South Africa
Income Tax Paid, by Individual Jurisdiction [Line Items]
Income taxes paid (net of refunds received)	$ (57,000)