Equity Method Investments and Variable Interest Entities (Contract Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2018
Schedule of Equity Method Investments [Line Items]
Accounts receivable, net of allowance for doubtful accounts	$ 938	$ 927	$ 667
Contract assets	215	185
Contract liabilities	484	463	$ 377
Accounts payable	572	546
Transactions with Related Parties
Schedule of Equity Method Investments [Line Items]
Accounts receivable, net of allowance for doubtful accounts	49	43
Contract assets	2	1
Contract liabilities	33	38
Accounts payable	$ 0	$ 2