Business segment data - Schedule of Operating Revenues Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 351,186	$ 344,471	$ 1,026,019	$ 932,746
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	361,215	353,587	1,069,656	972,190
Corporate, Non-Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	179	22	358	59
Intersegment eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ (10,208)	$ (9,138)	$ (43,995)	$ (39,503)