Related Parties (Details) - TTX Company [Member] - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Related Party Transaction [Line Items]
Equity Method Investment, Ownership Percentage	36.79%		36.79%
Equity Method Investments	$ 1,600		$ 1,600		$ 1,500
Related Party Transaction, Expenses from Transactions with Related Party	95	$ 88	191	$ 184
Accounts Payable, Related Parties, Current	$ 62		$ 62		$ 59

Amount for accounts payable to related parties. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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