Receivables and allowance for expected credit losses - Schedule of Accounts Receivable, Allowance for Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Current expected credit loss provision					$ 3,179	$ 3,103
Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 3,104	$ 1,839	$ 2,648	$ 1,603	1,839	1,603
Current expected credit loss provision	27	3,152	405	2,698
Less write-offs charged against the allowance	1,335	2,305	1,432	2,114
Credit loss recoveries collected	239	418	276	461
Ending balance	2,035	3,104	1,897	2,648	2,035	1,897
Electric | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	542	473	684	414	473	414
Current expected credit loss provision	178	939	190	782
Less write-offs charged against the allowance	333	1,036	463	659
Credit loss recoveries collected	74	166	80	147
Ending balance	461	542	491	684	461	491
Natural gas distribution | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	2,562	1,366	1,964	1,189	1,366	1,189
Current expected credit loss provision	(151)	2,213	215	1,916
Less write-offs charged against the allowance	1,002	1,269	969	1,455
Credit loss recoveries collected	165	252	196	314
Ending balance	1,574	2,562	1,406	1,964	1,574	1,406
Pipeline | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	0	0	0	0	0	0
Current expected credit loss provision	0	0	0	0
Less write-offs charged against the allowance	0	0	0	0
Credit loss recoveries collected	0	0	0	0
Ending balance	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0