Leases - Supplemental Cash Flow Information Related to Leases (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($)
Cash paid for amounts included in the measurement of lease obligations:
Operating Leases, Operating cash flows	$ 314
Operating Leases, Financing cash flows	0
Finance Leases, Operating cash flows	16
Finance Leases, Financing cash flows	52
Noncash transactions:
Operating Leases, Leased assets recognized for new lease obligations incurred	10
Finance Leases, Leased assets recognized for new lease obligations incurred	$ 0