Revenue Recognition - Receivables and Contract Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Accounts receivable – third parties, net	$ 12		$ 19
Deferred revenue	0		8
Third Parties
Disaggregation of Revenue [Line Items]
Accounts receivable – third parties, net	11	$ 19	19	$ 17
Deferred revenue	0	8	8	6	$ 6
Related Parties
Disaggregation of Revenue [Line Items]
Accounts receivable – third parties, net	24	21	21	19
Deferred revenue	$ 0	$ 3	$ 3	$ 9	$ 14