Leases - Schedule of Contractual Future Lease Obligations (Detail) $ in Millions	Mar. 31, 2019 USD ($)
Contractual Obligation, Fiscal Year Maturity Schedule [Abstract]
Operating leases, One year or Less	$ 286
Operating leases, Over One Through Two Years	260
Operating leases, Over Two Through Three Years	228
Operating leases, Over Three Through Four Years	191
Operating leases, Over Four Through Five Years	148
Operating leases, Thereafter	466
Operating leases	1,579
Operating leases	1,579
Operating leases, amounts representing interest	(183)
Operating leases, lease liabilities	1,396
Finance leases, One Year or Less	17
Finance leases, Over One Through Two Years	15
Finance leases, Over Two Through Three Years	12
Finance leases, Over Three Through Four Years	10
Finance leases, Over Four Through Five Years	9
Finance leases, thereafter	36
Finance leases	99
Finance leases, Amounts representing interest	(34)
Finance leases, lease liabilities	$ 65