Stock-Based Compensation - Assumptions Used to Determine Fair Value of Options (Details) - Stock Options	12 Months Ended
	May 31, 2023	May 31, 2022	May 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.80%	0.80%	0.40%
Dividend yield	1.10%	1.20%	1.10%
Expected volatility of Cintas' common stock	26.00%	25.20%	23.50%
Expected life of the option in years	5 years 6 months	5 years 6 months	5 years 6 months