Summary of significant accounting policies, Revenue recognition - Remaining performance obligations (Details) $ in Millions	Dec. 31, 2023 USD ($)
Remaining performance obligations [Abstract]
Remaining performance obligations	$ 8.2
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Remaining performance obligations [Abstract]
Remaining performance obligations	$ 7.9
Expected timing of satisfaction, period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Remaining performance obligations [Abstract]
Remaining performance obligations	$ 0.2
Expected timing of satisfaction, period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Remaining performance obligations [Abstract]
Remaining performance obligations
Expected timing of satisfaction, period	12 months