Debentures - Change in Fair Value (Details) - USD ($) $ in Millions	12 Months Ended
Feb. 28, 2021	Feb. 29, 2020	Feb. 28, 2019	Sep. 01, 2020
Debt Instrument [Line Items]
Long-term debentures (note 7)	$ 720	$ 0
1.75% Debenture
Debt Instrument [Line Items]
Face amount of debt	365			$ 365
Total decrease (increase) in fair value of the debenture	355	$ 0	$ 0
Long-term debentures (note 7)	$ 720			$ 456

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

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