Supplemental information - Summary of Dividends per Share (Details) - $ / shares	3 Months Ended						9 Months Ended
	May 31, 2022	Feb. 28, 2022	Nov. 30, 2021	May 31, 2021	Feb. 28, 2021	Nov. 30, 2020	May 31, 2022	May 31, 2021
Cash and Cash Equivalents [Abstract]
Cash dividends declared (in dollars per share)	$ 0.4775	$ 0.4775	$ 0.4775	$ 0.4675	$ 0.4675	$ 0.4675	$ 1.4325	$ 1.4025