Receivables and allowance for expected credit losses - Accounts Receivable, Allowance for Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Current expected credit loss provision					$ 2,968	$ 5,862
Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 10,156	$ 9,570	$ 6,351	$ 4,154	9,570	4,154
Current expected credit loss provision	681	2,287	2,097	3,765
Less write-offs charged against the allowance	1,973	2,162	1,873	1,943
Credit loss recoveries collected	289	461	298	375
Ending balance	9,153	10,156	6,873	6,351	9,153	6,873
Electric | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	684	414	468	375	414	375
Current expected credit loss provision	190	782	182	615
Less write-offs charged against the allowance	463	659	316	667
Credit loss recoveries collected	80	147	79	145
Ending balance	491	684	413	468	491	413
Natural gas distribution | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,964	1,189	2,943	1,615	1,189	1,615
Current expected credit loss provision	214	1,916	90	2,324
Less write-offs charged against the allowance	969	1,455	1,454	1,225
Credit loss recoveries collected	196	314	161	229
Ending balance	1,405	1,964	1,740	2,943	1,405	1,740
Pipeline | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	0	0	2	2	0	2
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	2	2	0	2
Construction services | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	7,508	7,967	2,938	2,162	7,967	2,162
Current expected credit loss provision	277	(411)	1,825	826
Less write-offs charged against the allowance	541	48	103	51
Credit loss recoveries collected	13	0	58	1
Ending balance	$ 7,257	$ 7,508	$ 4,718	$ 2,938	$ 7,257	$ 4,718