Leases - Supplemental Balance Sheet Information Related to Leases (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Operating leases
Operating lease right-of-use assets	$ 506	$ 500
Total operating lease liabilities	583	$ 600
Finance leases
Property, plant and equipment, net	473		$ 468
Other intangible assets, gross	6,827		6,693
Accumulated amortization	(3,728)		(3,590)
Other intangible assets, net	5,020		5,024
Accounts payable and other current liabilities	1,071		1,119
Long-term debt and finance lease obligations	8,242		$ 8,280
Total finance lease liabilities	163
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from finance leases	(2)
Operating cash flows from operating leases	(28)
Financing cash flows from finance leases	(16)
Right-of-use assets obtained in exchange for new finance lease liabilities	8
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 30
Weighted-average remaining lease term--finance leases	4 years
Weighted-average remaining lease term--operating leases	10 years
Weighted-average discount rate--finance leases	4.58%
Weighted-average discount rate--operating leases	4.55%
Finance Leases
Finance leases
Property, plant and equipment, gross	$ 352
Accumulated depreciation	(156)
Property, plant and equipment, net	196
Other intangible assets, gross	19
Accumulated amortization	(7)
Other intangible assets, net	12
Accounts payable and other current liabilities	67
Long-term debt and finance lease obligations	96
Other Current Liabilities
Operating leases
Total operating lease liabilities	114
Operating Lease Liabilities
Operating leases
Total operating lease liabilities	$ 469