Pension and Other Postretirement Benefits - Schedule of Reconciliation of Benefit Obligations, Plan Assets and Funded Status of the Plans (Details) - USD ($) $ in Millions	12 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Change in plan assets:
Fair value of plan assets at beginning of year
Fair value of plan assets at end of year
Pension Benefits
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	1,339.3	1,264.5
Service cost	9.9	9.2	$ 9.5
Interest cost	46.9	53.0	52.1
Benefits paid	(80.6)	(88.7)
Actuarial loss	71.1	101.3
Plan settlements	(47.1)	0.0
Plan settlements	3.6	0.0
Projected benefit obligation at end of year	1,343.1	1,339.3	1,264.5
Change in plan assets:
Fair value of plan assets at beginning of year	964.7	972.5
Actual return	76.2	72.2
Benefits paid	(80.9)	(88.7)
Contributions	9.9	8.7
Plan settlements	(46.5)	0.0
Fair value of plan assets at end of year	923.4	964.7	972.5
Funded status of the plans	(419.7)	(374.6)
Amounts recognized in the consolidated balance sheets:
Accrued liabilities - current	(20.2)	(3.4)
Accrued pension and postretirement benefits - noncurrent	(399.5)	(371.2)
Amounts recognized in the consolidated balance sheets	(419.7)	(374.6)
Other Benefits
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	255.8	241.5
Service cost	2.6	2.3	2.6
Interest cost	9.0	10.1	9.5
Benefits paid	(12.6)	(12.6)
Actuarial loss	9.4	14.5
Plan settlements	0.0	0.0
Plan settlements	0.0	0.0
Projected benefit obligation at end of year	264.2	255.8	241.5
Change in plan assets:
Fair value of plan assets at beginning of year	119.0	117.9
Actual return	2.9	10.5
Benefits paid	(12.4)	(12.6)
Contributions	3.3	3.2
Plan settlements	0.0	0.0
Fair value of plan assets at end of year	112.8	119.0	$ 117.9
Funded status of the plans	(151.4)	(136.8)
Amounts recognized in the consolidated balance sheets:
Accrued liabilities - current	(14.0)	(14.7)
Accrued pension and postretirement benefits - noncurrent	(137.4)	(122.1)
Amounts recognized in the consolidated balance sheets	$ (151.4)	$ (136.8)

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

Name:	us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.