Risk Management and Derivatives: Utilities (Details) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020 USD ($) MMBTU mW	Dec. 31, 2019 MMBTU mW
Derivative [Line Items]
Credit Risk Derivative Liabilities, at Fair Value | $	$ 500
Natural Gas, Distribution | Cash Flow Hedging
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	1,274,900
Natural Gas, Distribution | Natural gas futures purchased
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	1,930,000	1,450,000
Derivative, Remaining Maturity	6 months	12 months
Natural Gas, Distribution | Natural gas options purchased, net
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	8,320,000	3,240,000
Derivative, Remaining Maturity	6 months	3 months
Natural Gas, Distribution | Natural gas basis swaps purchased
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	1,780,000	1,290,000
Derivative, Remaining Maturity	6 months	12 months
Natural Gas, Distribution | Natural gas over-the-counter swaps, net
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	4,525,100	4,600,000
Derivative, Remaining Maturity	20 months	24 months
Natural Gas, Distribution | Natural gas physical contracts, net
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	23,350,287	13,548,235
Derivative, Remaining Maturity	13 months	12 months
Electricity | Electric wholesale contracts
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | mW	55,225	0
Derivative, Remaining Maturity	3 months	0 months