Accounting Policies - CECL Table (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for doubtful accounts	$ 15,358	$ 8,497
Accounts Receivable, Credit Loss Expense (Reversal)	10,985
Accounts Receivable, Allowance for Credit Loss, Writeoff	5,306
Accounts Receivable, Allowance for Credit Loss, Recovery	1,182
Electric
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for doubtful accounts	899	328
Accounts Receivable, Credit Loss Expense (Reversal)	1,517
Accounts Receivable, Allowance for Credit Loss, Writeoff	1,289
Accounts Receivable, Allowance for Credit Loss, Recovery	343
Natural gas distribution
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for doubtful accounts	2,571	1,056
Accounts Receivable, Credit Loss Expense (Reversal)	3,187
Accounts Receivable, Allowance for Credit Loss, Writeoff	2,511
Accounts Receivable, Allowance for Credit Loss, Recovery	839
Pipeline
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for doubtful accounts	2	0
Accounts Receivable, Credit Loss Expense (Reversal)	2
Accounts Receivable, Allowance for Credit Loss, Writeoff	0
Accounts Receivable, Allowance for Credit Loss, Recovery	0
Construction materials and contracting
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for doubtful accounts	6,164	5,357
Accounts Receivable, Credit Loss Expense (Reversal)	1,447
Accounts Receivable, Allowance for Credit Loss, Writeoff	640
Accounts Receivable, Allowance for Credit Loss, Recovery	0
Construction services
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for doubtful accounts	5,722	$ 1,756
Accounts Receivable, Credit Loss Expense (Reversal)	4,832
Accounts Receivable, Allowance for Credit Loss, Writeoff	866
Accounts Receivable, Allowance for Credit Loss, Recovery	$ 0