Leases - Supplemental Cash Flow Information Related to Leases (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Cash paid for amounts included in the measurement of lease obligations:
Operating Leases, Operating cash flows	$ 419
Operating Leases, Financing cash flows	0
Finance Leases, Operating cash flows	21
Finance Leases, Financing cash flows	55
Noncash transactions:
Operating Leases, Leased assets recognized for new lease obligations incurred	14
Finance Leases, Leased assets recognized for new lease obligations incurred	$ 0