Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Regulated Operating Revenue, Other	$ 5,704	$ 6,731	$ 11,713	$ 17,974
Revenues	651,679	670,930	1,697,809	1,785,769
Revenue from Contract with Customer, Including Assessed Tax	635,724	644,987	1,651,936	1,740,785
Electricity, US Regulated [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	433,112	463,219	1,040,805	1,100,408
Natural Gas, US Regulated [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	168,117	145,222	533,753	467,782
Other Revenue From Contracts with Customers [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	34,495	36,546	77,378	172,595
Decoupling over-collection [Domain]
Disaggregation of Revenue [Line Items]
Regulated Operating Revenue, Other	19,750	4,351	20,900	(20,880)
Other Non-606 Revenue [Member]
Disaggregation of Revenue [Line Items]
Regulated Operating Revenue, Other	(3,795)	21,592	24,973	65,864
Subsidiaries [Member]
Disaggregation of Revenue [Line Items]
Regulated Operating Revenue, Other	5,704	6,731	11,713	17,974
Revenues	$ 651,679	$ 670,930	$ 1,697,809	$ 1,785,769