Accrued Dividends Payable And Dividends per Common Share (Narrative) (Details) $ in Millions	9 Months Ended
	Feb. 29, 2020 USD ($)
Earnings Per Share Reconciliation [Abstract]
Number of days after first, second and third quarter dividends paid	60 days
Number of days after fourth quarter dividends paid	65 days
Number of days dividends paid following record date	15 days
Percentage of net income loss used to compute accrued dividends	33.00%
Cumulative losses to be recovered prior to paying dividend	$ 61.9