Long-Term Debt (Schedule of Total Interest Expense Recognized) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Amortization of debt discount		$ 4	$ 4	$ 3
Amortization of deferred financing costs		9	11	7
Total interest expense	[1]	154	113	87
MIC Corporate | 2.00% Convertible Senior Notes due October 2023
Debt Instrument [Line Items]
Contractual interest expense		8	8	8
Amortization of debt discount		4	4	3
Amortization of deferred financing costs		1	1	2
Total interest expense		$ 13	$ 13	$ 13

[1] Interest expense includes losses on derivative instruments of $13 million and gains on derivative instruments of $8 million and $2 million in 2019, 2018 and 2017, respectively.