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		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator:
Net income from continuing operations attributable to MIC	$ 15	$ 2	$ 85	$ 69
Diluted net income from continuing operations attributable to MIC	15	2	85	69
Net income from discontinued operations attributable to MIC	$ 46	$ 20	$ 57	$ 68
Denominator:
Weighted average number of shares outstanding: basic (in shares)	86,276,237	85,378,088	86,075,394	85,095,956
Dilutive effect of restricted stock unit grants (in shares)	27,457	20,478	25,628	13,257
Weighted average number of shares outstanding: diluted (in shares)	86,303,694	85,398,566	86,101,022	85,109,213
Income per share:
Basic income per share from continuing operations attributable to MIC (in dollars per share)	$ 0.18	$ 0.02	$ 0.99	$ 0.81
Basic income per share from discontinued operations attributable to MIC (in dollars per share)	0.53	0.23	0.67	0.80
Basic income per share attributable to MIC (in dollars per share)	0.71	0.25	1.66	1.61
Diluted income per share from continuing operations attributable to MIC (in dollars per share)	0.18	0.02	0.99	0.81
Diluted income per share from discontinued operations attributable to MIC (in dollars per share)	0.53	0.23	0.67	0.80
Diluted income per share attributable to MIC (in dollars per share)	$ 0.71	$ 0.25	$ 1.66	$ 1.61