Paychex, Inc. Quarterly report pursuant to Section 13 or 15(d)

Short-term Financing (Credit Facility Amount Borrowed) (Details) - Revolving Credit Facility [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2018	Feb. 28, 2017	Feb. 28, 2018	Feb. 28, 2017
JPM $1 Billion Credit Facility [Member] \| JP Morgan Chase Bank, N.A. [Member]
Line of Credit Facility [Line Items]
Number of days borrowed	2 days	8 days	21 days	27 days
Maximum amount borrowed	$ 200.0	$ 250.0	$ 700.0	$ 350.0
Weighted-average amount borrowed	$ 125.0	$ 81.3	$ 311.9	$ 183.3
Weighted-average interest rate	4.25%	2.24%	4.24%	2.68%
JPM $500 Million Credit Facility [Member] \| JP Morgan Chase Bank, N.A. [Member]
Line of Credit Facility [Line Items]
Number of days borrowed	19 days		39 days
Maximum amount borrowed	$ 75.0		$ 400.0
Weighted-average amount borrowed	$ 75.0		$ 147.2
Weighted-average interest rate	2.19%		2.69%
PNC $150 Million Credit Facility [Member] \| PNC Bank, National Association [Member]
Line of Credit Facility [Line Items]
Number of days borrowed	90 days	90 days	269 days	267 days
Maximum amount borrowed	$ 59.9	$ 55.6	$ 59.9	$ 55.6
Weighted-average amount borrowed	$ 59.1	$ 55.3	$ 57.6	$ 52.6
Weighted-average interest rate	2.01%	1.27%	1.83%	1.13%