Employee Benefit Plans - Defined Benefit Pension Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Benefit expense	$ 5.2	$ 4.4	$ 4.9
Benefit obligation	59.8	50.8	42.8
Rabbi Trust assets	54.5	41.9
SORP | Supplemental Employee Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Benefit expense	4.8	3.9	4.3
Benefit obligation	53.8	45.5	38.3
SERP | Supplemental Employee Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Benefit expense	0.4	0.5	0.6
Benefit obligation	$ 6.0	$ 5.4	$ 4.5