Reportable Segments (Schedule of Capital Expenditures) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Capital expenditures	$ 70	$ 45	$ 172	$ 131
IMTT
Segment Reporting Information [Line Items]
Capital expenditures	47	18	111	42
Atlantic Aviation
Segment Reporting Information [Line Items]
Capital expenditures	17	16	44	52
MIC Hawaii
Segment Reporting Information [Line Items]
Capital expenditures	5	6	15	17
Corporate and Other
Segment Reporting Information [Line Items]
Capital expenditures	$ 1	$ 5	$ 2	$ 20