Revenue - Contract and Contract Related Liabilities - Footnotes (Details) - Customer Deposits and Other Deferred Revenue [Member] - USD ($) $ in Millions		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Contract and Contract Related Liabilities [Line Items]
Contract and contract related, liability	[1]	$ 827	$ 714	$ 633
Mall [Member]
Contract and Contract Related Liabilities [Line Items]
Contract and contract related, liability		$ 152	$ 145	$ 131

[1] Of this amount, $152 million, $145 million and $131 million as of December 31, 2018, December 31, 2017 and January 1, 2017, respectively, relates to mall deposits that are accounted for based on lease terms usually greater than one year.