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

Funds Held for Clients and Corporate Investments (Securities in Unrealized Loss Position) (Details)

Funds Held for Clients and Corporate Investments (Securities in Unrealized Loss Position) (Details) - USD ($) $ in Millions	Feb. 29, 2020	May 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses		$ (2.7)
Total, Gross unrealized losses		(2.7)
Securities in an unrealized loss position for less than twelve months, Fair value		9.4
Securities in an unrealized loss position for more than twelve months, Fair value	$ 1.4	558.5
Total, Fair value		567.9
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses		(0.9)
Total, Gross unrealized losses		(0.9)
Securities in an unrealized loss position for less than twelve months, Fair value		1.5
Securities in an unrealized loss position for more than twelve months, Fair value		133.8
Total, Fair value		135.3
General Obligation Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses		(0.3)
Total, Gross unrealized losses		(0.3)
Securities in an unrealized loss position for less than twelve months, Fair value		3.0
Securities in an unrealized loss position for more than twelve months, Fair value		168.3
Total, Fair value		171.3
Pre-Refunded Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities in an unrealized loss position for less than twelve months, Fair value		0.1
Securities in an unrealized loss position for more than twelve months, Fair value		1.6
Total, Fair value		1.7
Revenue Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses		(0.2)
Total, Gross unrealized losses		(0.2)
Securities in an unrealized loss position for less than twelve months, Fair value		0.1
Securities in an unrealized loss position for more than twelve months, Fair value		79.2
Total, Fair value		79.3
U.S. Government Agency And Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses		(1.3)
Total, Gross unrealized losses		(1.3)
Securities in an unrealized loss position for less than twelve months, Fair value		4.7
Securities in an unrealized loss position for more than twelve months, Fair value		175.6
Total, Fair value		$ 180.3