Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue from Contract with Customer, Including Assessed Tax	$ 3,311,090	$ 3,222,093
Regulated Operating Revenue, Other	28,718	39,829	$ 41,854
Revenues	3,401,130	3,346,496	$ 3,460,276
Electricity, US Regulated [Member]
Revenue from Contract with Customer, Including Assessed Tax	2,132,522	2,138,008
Natural Gas, US Regulated [Member]
Revenue from Contract with Customer, Including Assessed Tax	870,457	849,898
Other Revenue From Contracts with Customers [Member]
Revenue from Contract with Customer, Including Assessed Tax	308,111	234,187
Decoupling over-collection [Domain]
Regulated Operating Revenue, Other	(18,634)	(22,852)
Other Non-606 Revenue [Member]
Regulated Operating Revenue, Other	$ 108,674	$ 147,255