Income per Share (Schedule of Reconciliation of the basic and diluted income (loss) per share computations (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Jul. 15, 2019
Numerator:
Net income from continuing operations attributable to MIC	$ 11	$ 64
Diluted net income from continuing operations attributable to MIC	11	69
Basic and diluted net income from discontinued operations attributable to MIC	$ 0	$ 6
Denominator:
Weighted average number of shares outstanding: basic (in shares)	86,686,972	85,872,132
Dilutive effect of restricted stock unit grants (in shares)	31,095	23,646
Weighted average number of shares outstanding: diluted (in shares)	86,718,067	93,913,267
Income per share:
Basic income per share from continuing operations attributable to MIC (in dollars per share)	$ 0.13	$ 0.75
Basic income per share from discontinued operations attributable to MIC (in dollars per share)	0	0.07
Basic income per share attributable to MIC (in dollars per share)	0.13	0.82
Diluted income per share from continuing operations attributable to MIC (in dollars per share)	0.13	0.73
Diluted income per share from discontinued operations attributable to MIC (in dollars per share)	0	0.06
Diluted income per share attributable to MIC (in dollars per share)	$ 0.13	$ 0.79
2.875% Convertible Senior Notes July 2019
Class of Stock [Line Items]
Interest rate, stated percentage	2.875%		2.875%
Numerator:
Interest expense attributable to convertible Senior Notes, net of taxes	$ 0	$ 2
Denominator:
Dilutive effect of convertible Senior Notes (in shares)	0	4,383,316
2.00% Convertible Senior Notes due October 2023
Class of Stock [Line Items]
Interest rate, stated percentage	2.00%
Numerator:
Interest expense attributable to convertible Senior Notes, net of taxes	$ 0	$ 3
Denominator:
Dilutive effect of convertible Senior Notes (in shares)	0	3,634,173