Receivables and allowance for expected credit losses - Schedule of Accounts Receivable, Allowance for Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Current expected credit loss provision							$ 5,404	$ 4,953
Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 2,035	$ 3,104	$ 1,839	$ 1,897	$ 2,648	$ 1,603	1,839	1,603
Current expected credit loss provision	2,225	27	3,152	1,850	405	2,698
Less write-offs charged against the allowance	3,142	1,335	2,305	2,715	1,432	2,114
Credit loss recoveries collected	296	239	418	341	276	461
Ending balance	1,414	2,035	3,104	1,373	1,897	2,648	1,414	1,373
Electric | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	461	542	473	491	684	414	473	414
Current expected credit loss provision	646	178	939	520	190	782
Less write-offs charged against the allowance	688	333	1,036	594	463	659
Credit loss recoveries collected	76	74	166	86	80	147
Ending balance	495	461	542	503	491	684	495	503
Natural gas distribution | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,574	2,562	1,366	1,406	1,964	1,189	1,366	1,189
Current expected credit loss provision	1,579	(151)	2,213	1,330	215	1,916
Less write-offs charged against the allowance	2,454	1,002	1,269	2,121	969	1,455
Credit loss recoveries collected	220	165	252	255	196	314
Ending balance	919	1,574	2,562	870	1,406	1,964	919	870
Pipeline | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	0	0	0	0	0	0	0	0
Current expected credit loss provision	0	0	0	0	0	0
Less write-offs charged against the allowance	0	0	0	0	0	0
Credit loss recoveries collected	0	0	0	0	0	0
Ending balance	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0