CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended	6 Months Ended
Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Statement of Stockholders' Equity [Abstract]
Dividends paid per share	$ 0.65625	$ 0.65625	$ 1.3125	$ 1.3125

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