Leases - Summary of Lease Costs (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Leases [Abstract]
Amortization of right-of-use assets	$ 0	$ 1
Interest on lease liabilities	1	1
Operating lease cost	52	157
Total lease cost	$ 53	$ 159