Related Party Transactions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Cash distributions declared and paid	$ 4,425	$ 5,450	$ 4,575
Revenues earned for services provided to related parties	158	152	139
Expenditures to related parties	$ 386	381	342
Equity Method Investments and Joint Ventures [Abstract]
Ownership Percentage in TTX Company	17.30%
Investments related to TTX	$ 656	609
Parent Company
Related Party Transaction [Line Items]
Cash distributions declared and paid	4,400	5,500	4,600
Tax Refunds from Parent Company	1	222	29
Tax payments to parent company	934	912	$ 1,600
Payable to parent company	$ 31
Earliest Tax Year | Parent Company
Related Party Transaction [Line Items]
Tax payable to parent by reporting entity		$ 54