Acquisition Activity (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	May 31, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Repayment of debt		$ 1,290,000	$ 1,164,000	$ 1,094,000
InfraREIT Acquisition related costs				9,000
Revenue from contracts		4,764,000	4,511,000	4,347,000
Net income		$ 770,000	$ 713,000	651,000
InfraREIT [Member]
Business Acquisition [Line Items]
Outstanding debt acquired	$ 953,000
Repayment of debt	602,000
InfraREIT Acquisition related costs				9,000
Revenue from contracts				156,000
Net income				58,000
Pro forma revenues				$ 4,431,000
InfraREIT [Member] | Secured Debt [Member]
Business Acquisition [Line Items]
Outstanding debt acquired	$ 351,000