Leases - Additional Information (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
Leases [Abstract]
Finance lease, right-of-use asset	$ 89	$ 89
Finance lease liability	93	93
Finance lease expense	$ 6	$ 17