Intangible Assets and Goodwill (Schedule of Goodwill) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Goodwill acquired in business combinations, net of disposals, at December 31, 2018		$ 2,172
Accumulated impairment charges		(126)
Other	$ 0	(3)
Goodwill [Roll Forward]
Balance at period start	2,043
Other	0	(3)
Balance at period end	2,043	2,043
IMTT
Goodwill [Line Items]
Goodwill acquired in business combinations, net of disposals, at December 31, 2018		1,430
Accumulated impairment charges		0
Other	1	(3)
Goodwill [Roll Forward]
Balance at period start	1,427
Other	1	(3)
Balance at period end	1,428	1,427
Atlantic Aviation
Goodwill [Line Items]
Goodwill acquired in business combinations, net of disposals, at December 31, 2018		619
Accumulated impairment charges		(123)
Other	(1)	0
Goodwill [Roll Forward]
Balance at period start	496
Other	(1)	0
Balance at period end	495	496
MIC Hawaii
Goodwill [Line Items]
Goodwill acquired in business combinations, net of disposals, at December 31, 2018		123
Accumulated impairment charges		(3)
Other	0	0
Goodwill [Roll Forward]
Balance at period start	120
Other	0	0
Balance at period end	$ 120	$ 120