Consolidated Statements of Changes in Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended
Feb. 29, 2020	Nov. 30, 2019	Aug. 31, 2019	Feb. 28, 2019	Nov. 30, 2018	Aug. 31, 2018
Statement of Stockholders' Equity [Abstract]
Preferred dividends per share	$ 2.00	$ 2.05	$ 2.25	$ 2.16	$ 2.10	$ 2.06

Aggregate dividends paid during the period for each share of preferred stock outstanding.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration