Paychex, Inc. Annual report pursuant to Section 13 and 15(d)

Short-term Financing (Credit Facility Amount Borrowed) (Details) - Revolving Credit Facility [Member] - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017
JPM $1 Billion Credit Facility [Member] \| JP Morgan Chase Bank, N.A. [Member]
Line of Credit Facility [Line Items]
Number of days borrowed	22 days	30 days
Maximum amount borrowed	$ 700.0	$ 450.0
Weighted-average amount borrowed	$ 319.1	$ 196.7
Weighted-average interest rate	4.27%	2.89%
JPM $500 Million Credit Facility [Member] \| JP Morgan Chase Bank, N.A. [Member]
Line of Credit Facility [Line Items]
Number of days borrowed	42 days
Maximum amount borrowed	$ 400.0
Weighted-average amount borrowed	$ 144.8
Weighted-average interest rate	2.80%
PNC $150 Million Credit Facility [Member] \| PNC Bank, National Association [Member]
Line of Credit Facility [Line Items]
Number of days borrowed	358 days	353 days
Maximum amount borrowed	$ 59.9	$ 55.6
Weighted-average amount borrowed	$ 57.2	$ 52.8
Weighted-average interest rate	1.94%	1.21%