Reportable Segments (Schedule of Assets of Reportable Segments) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Property, Equipment, Land and Leasehold Improvements, net	$ 3,153	$ 3,141
Goodwill	2,043	2,043
Total Assets	6,924	7,444
Operating Segments
Segment Reporting Information [Line Items]
Property, Equipment, Land and Leasehold Improvements, net	3,153	3,141
Goodwill	2,043	2,043
Total Assets	6,924	6,796
IMTT | Operating Segments
Segment Reporting Information [Line Items]
Property, Equipment, Land and Leasehold Improvements, net	2,273	2,249
Goodwill	1,427	1,427
Total Assets	4,135	4,020
Atlantic Aviation | Operating Segments
Segment Reporting Information [Line Items]
Property, Equipment, Land and Leasehold Improvements, net	567	565
Goodwill	496	496
Total Assets	2,040	1,676
MIC Hawaii | Operating Segments
Segment Reporting Information [Line Items]
Property, Equipment, Land and Leasehold Improvements, net	303	300
Goodwill	120	120
Total Assets	528	501
Corporate and Other | Operating Segments
Segment Reporting Information [Line Items]
Property, Equipment, Land and Leasehold Improvements, net	10	27
Goodwill	0	0
Total Assets	221	599
Assets held for sale | Segment Reconciling Items
Segment Reporting Information [Line Items]
Property, Equipment, Land and Leasehold Improvements, net	0	0
Goodwill	0	0
Total Assets	$ 0	$ 648