Investments in Operating Leases, Net - Investments in Operating Leases, Net (Parenthetical) (Details) - USD ($) $ in Billions	Sep. 30, 2020	Mar. 31, 2020
Securitized investments in operating leases [Member]
Property Subject To Or Available For Operating Lease [Line Items]
Investments in operating leases	$ 9.2	$ 7.9

Amount before accumulated depreciation of physical assets used in the normal conduct of business to produce goods and services subject to or available for lease.

Reference 1: 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=121578510&loc=d3e41551-112718

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121589968&loc=d3e41457-112716

Name:	us-gaap_PropertySubjectToOrAvailableForOperatingLeaseGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant