Long-Term Debt (Schedule of Interest Rate Swap Agreements) (Details) - Interest Rate Swap Contracts [Member] - USD ($) $ in Millions		1 Months Ended	6 Months Ended						12 Months Ended
	Mar. 27, 2019	Nov. 30, 2019	Jun. 30, 2020		Dec. 31, 2019		Jun. 30, 2019		Dec. 31, 2019		Nov. 05, 2019	Dec. 31, 2018	[1]
Derivative [Line Items]
Balance at the beginning of the period			$ 550		$ 171		$ 650		$ 650
Terminated	$ (479)	$ (171)			(171)		(479)
Entered into effect					550
Balance at the end of the period	$ 650		$ 550		$ 550		$ 171		$ 550
Weighted Average Fixed Rate (as a percent)			1.615%	[1]	1.615%	[1]	1.493%	[1]	1.615%	[1]	1.615%	1.493%

[1] Before the application of the applicable borrowing margin.