Revenue Recognition - Receivables and Contract Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Jan. 01, 2018
Disaggregation of Revenue [Line Items]
Accounts receivable – third parties, net	$ 20	$ 12
Contract assets – related parties	233	0
Deferred revenue	4	0
Third Parties
Disaggregation of Revenue [Line Items]
Accounts receivable – third parties, net	19	11	$ 11		$ 19
Deferred revenue	4	0	0	$ 8	8
Related Parties
Disaggregation of Revenue [Line Items]
Accounts receivable – third parties, net	18	24	24		21
Contract assets – related parties	233		0
Deferred revenue	$ 19	$ 0	$ 0	$ 3	$ 3