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

Funds Held for Clients and Corporate Investments (Securities in Unrealized Loss Position) (Details) - USD ($) $ in Millions	Nov. 30, 2020	May 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Securities in an unrealized loss position for less than twelve months, Gross unrealized losses	$ (0.5)	$ (1.7)
Total, Gross unrealized losses	(0.5)	(1.7)
Securities in an unrealized loss position for less than twelve months, Fair value	127.0	66.8
Total, Fair value	127.0	66.8
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities in an unrealized loss position for less than twelve months, Gross unrealized losses		(0.1)
Total, Gross unrealized losses		(0.1)
Securities in an unrealized loss position for less than twelve months, Fair value	1.0	6.5
Total, Fair value	1.0	6.5
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities in an unrealized loss position for less than twelve months, Gross unrealized losses	(0.5)	(1.6)
Total, Gross unrealized losses	(0.5)	(1.6)
Securities in an unrealized loss position for less than twelve months, Fair value	113.3	60.3
Total, Fair value	113.3	$ 60.3
U.S. Government Agency And Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities in an unrealized loss position for less than twelve months, Fair value	12.7
Total, Fair value	$ 12.7