Leases - Additional Information (Detail) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Leases [Abstract]
Operating lease asset	$ 623	$ 623
Operating lease liability	702	702
Operating lease cost	29	59
Variable lease cost	4	8
Short term lease cost	2	4
Lease liability cash payments	$ 30	$ 59