Debentures - Impact of Changes in Fair Value of Debentures (Details) - USD ($) $ in Millions	3 Months Ended
May 31, 2020	May 31, 2019
Debt Disclosure [Abstract]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	$ (1)	$ 28
Income (charge) associated with the change in fair value from instrument-specific credit components recorded in AOCL	8	(8)
Debenture total fair value adjustment	$ 7	$ 20

Amount, before tax and reclassification adjustment, of unrealized gain (loss) from increase (decrease) in instrument-specific credit risk of financial liability measured under fair value option.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14172-108612

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=116690757&loc=SL75136633-108610

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e637-108580

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (l)
-URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580

Name:	us-gaap_OtherComprehensiveIncomeLossFinancialLiabilityFairValueOptionUnrealizedGainLossArisingDuringPeriodBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration