Shareholders' equity - Narrative (Details) - ₩ / shares |
Mar. 31, 2026 |
Dec. 31, 2025 |
Mar. 31, 2025 |
Dec. 31, 2024 |
|---|---|---|---|---|
| Share Capital, Reserves And Other Equity Interest [Abstract] | ||||
| Number of shares authorized (in shares) | 200,000,000 | 200,000,000 | ||
| Number of shares issued (in shares) | 2,477,672 | 2,477,672 | ||
| Number of shares outstanding (in shares) | 2,477,672 | 2,477,672 | 2,477,672 | 2,477,672 |
| Par value per share (in KRW per share) | ₩ 10,000 | ₩ 10,000 |