Equipment held for lease (Detail) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Property Subject to or Available for Operating Lease [Line Items]
Equipment held for lease, gross	$ 23,037	$ 22,474
Equipment held for lease, accumulated depreciation	(8,378)	(7,873)
Equipment held for lease, net	14,659	14,601
Railcars [Member]
Property Subject to or Available for Operating Lease [Line Items]
Equipment held for lease, gross	9,525	9,402
Aircraft [Member]
Property Subject to or Available for Operating Lease [Line Items]
Equipment held for lease, gross	8,560	8,204
Other [Member]
Property Subject to or Available for Operating Lease [Line Items]
Equipment held for lease, gross	$ 4,952	$ 4,868

Amount of accumulated depreciation of lessor's underlying asset for which right to use has been conveyed to lessee under operating lease.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123405975&loc=d3e41551-112718

Reference 3: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=123422147&loc=d3e41460-112716

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=124258985&loc=SL77919398-209981

Name:	us-gaap_PropertySubjectToOrAvailableForOperatingLeaseAccumulatedDepreciation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant