Consolidated Statements of Changes in Equity (Parenthetical) - $ / shares	3 Months Ended
Aug. 31, 2019	Aug. 31, 2018
Statement of Stockholders' Equity [Abstract]
Preferred dividends per share	$ 2.25	$ 2.06

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

No definition available.

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