Unaudited Condensed Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Statement of Stockholders' Equity [Abstract]
Dividends declared per common share (in dollars per share)	$ 0.245	$ 0.22	$ 0.71	$ 0.64
Dividends declared per preferred share (in dollars per share)	$ 0	$ 0	$ 0.10	$ 0.10