Revenue Recognition - Contract Balances (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($)
Movement in Deferred Revenue [Roll Forward]
Deferred revenue, beginning balance	$ 8
Deferred revenue, ending balance	0
Third Parties
Movement in Deferred Revenue [Roll Forward]
Deferred revenue, beginning balance	8
Additions	0
Reductions	(8)
Deferred revenue, ending balance	0
Related Parties
Movement in Deferred Revenue [Roll Forward]
Deferred revenue, beginning balance	3
Additions	0
Reductions	(3)
Deferred revenue, ending balance	$ 0