Employee Benefit Plans - Other Post-retirement Benefit Plan (Details) - Executive Retiree Health Insurance Plan - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Jun. 30, 2019 |
Jun. 30, 2018 |
Jun. 30, 2017 |
|
| Defined Benefit Plan Disclosure [Line Items] | |||
| Defined benefit plan, maximum age eligibility | 65 years | ||
| Benefit expense | $ 0.5 | $ 0.4 | $ 0.3 |
| Benefit obligation | $ 5.2 | $ 5.3 | $ 4.9 |