Related Parties - Investments in Unconsolidated Subsidiaries, Equity Securities and Other (Balance Sheet and Earnings Activity) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Net revenues	$ 772	$ 834	$ 1,549	$ 1,406
Expenses	8	14	27	27
Receivables	751		751		$ 523
Payables	9		9		20
Megapolis Group
Schedule of Equity Method Investments [Line Items]
Net revenues	530	556	1,026	915
Receivables	534		534		375
Other
Schedule of Equity Method Investments [Line Items]
Net revenues	242	278	523	491
Expenses	8	$ 14	27	$ 27
Receivables	217		217		148
Payables	$ 9		$ 9		$ 20