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, 2021	Jun. 30, 2020	Jun. 30, 2019
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	1,343.1	1,339.3
Service cost	9.6	9.9	$ 9.2
Interest cost	39.4	46.9	53.0
Benefits paid	(92.5)	(80.6)
Actuarial (gain) loss	(25.3)	71.1
Plan settlements	(48.8)	(47.1)
Special termination benefits	0.0	3.6
Projected benefit obligation at end of year	1,225.5	1,343.1	1,339.3
Change in plan assets:
Fair value of plan assets at beginning of year	923.4	964.7
Actual return	193.7	76.2
Benefits paid	(92.6)	(80.9)
Contributions	23.7	9.9
Plan settlements	(48.8)	(46.5)
Fair value of plan assets at end of year	999.4	923.4	964.7
Funded status of the plans	(226.1)	(419.7)
Amounts recognized in the consolidated balance sheets:
Accrued liabilities - current	(3.5)	(20.2)
Accrued pension and postretirement benefits - noncurrent	(222.6)	(399.5)
Amounts recognized in the consolidated balance sheets	(226.1)	(419.7)
Other Benefits
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	264.2	255.8
Service cost	2.7	2.6	2.3
Interest cost	7.7	9.0	10.1
Benefits paid	(12.9)	(12.6)
Actuarial (gain) loss	(12.4)	9.4
Plan settlements	0.0	0.0
Special termination benefits	0.0	0.0
Projected benefit obligation at end of year	249.3	264.2	255.8
Change in plan assets:
Fair value of plan assets at beginning of year	112.8	119.0
Actual return	33.6	2.9
Benefits paid	(12.8)	(12.4)
Contributions	2.7	3.3
Plan settlements	0.0	0.0
Fair value of plan assets at end of year	136.3	112.8	$ 119.0
Funded status of the plans	(113.0)	(151.4)
Amounts recognized in the consolidated balance sheets:
Accrued liabilities - current	(14.4)	(14.0)
Accrued pension and postretirement benefits - noncurrent	(98.6)	(137.4)
Amounts recognized in the consolidated balance sheets	$ (113.0)	$ (151.4)

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.