Transactions with Affiliates Related Party Transations (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 31, 2020 USD ($)	Sep. 30, 2020 USD ($) employee	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) employee	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Related Party Transaction [Line Items]
Advances to affiliate, net		$ 581,700		$ 581,700
Advances from affiliate						$ 252,500
Related party transaction, rate				0.01%
Entity number of employees | employee		0		0
Expenses, related party		$ 91,000	$ 110,700	$ 269,500	$ 315,400
Equity distributions to parent				785,000	559,000
Cash contributions from Parent				65,000	0
Subsequent Event [Member]
Related Party Transaction [Line Items]
Equity distributions to parent	$ 235,000
Cash contributions from Parent	$ 50,000
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Operating revenues, related party		2,800	2,800	8,000	8,400
Cost of natural gas sales, related party		800	800	3,800	3,000
Reduction to expenses		$ (1,600)	$ (1,200)	$ (3,800)	$ (3,500)