Intangible Assets and Goodwill (Schedule of Goodwill) (Details) - USD ($) $ in Millions		6 Months Ended	12 Months Ended
	Dec. 31, 2019	Jun. 30, 2020	Dec. 31, 2019
Goodwill [Line Items]
Beginning balance		$ 2,043
Accumulated impairment charges	$ (126)		$ (126)
Other			(3)
Goodwill acquired	2,172	1
Ending balance	2,043	2,044	2,043
IMTT
Goodwill [Line Items]
Beginning balance		1,428
Accumulated impairment charges	0		0
Other			(2)
Goodwill acquired	1,430	0
Ending balance	1,428	1,428	1,428
Atlantic Aviation
Goodwill [Line Items]
Beginning balance		495
Accumulated impairment charges	(123)		(123)
Other			(1)
Goodwill acquired	619	1
Ending balance	495	496	495
MIC Hawaii
Goodwill [Line Items]
Beginning balance		120
Accumulated impairment charges	(3)		(3)
Other			0
Goodwill acquired	123	0
Ending balance	$ 120	$ 120	$ 120