Summary of significant accounting policies - Foreign Currency Translation and Transaction (Details)	Dec. 31, 2025 ¥ / $	Dec. 31, 2025 $ / $	Dec. 31, 2025 € / $	Dec. 31, 2025 ₨ / $	Dec. 31, 2024 ¥ / $	Dec. 31, 2024 $ / $	Dec. 31, 2024 € / $
Accounting Policies [Abstract]
Exchange rate on the balance sheet date	6.9835	1.3690	0.8500	89.8354	7.3094	1.4384	0.9600