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, 2018	Jun. 30, 2017	Jun. 30, 2016
Change in projected benefit obligation:
Curtailment gain		$ (0.5)
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	1,369.1	1,404.4
Service cost	9.5	20.5	$ 31.2
Interest cost	52.1	50.3	58.0
Benefits paid	(89.8)	(92.0)
Actuarial (gains) loss	(76.6)	39.3
Special termination benefits	0.2	0.6
Curtailment gain	0.0	(72.6)
Plan amendments	0.0	18.6
Projected benefit obligation at end of year	1,264.5	1,369.1	1,404.4
Change in plan assets:
Fair value of plan assets at beginning of year	987.6	885.1
Actual return	64.7	91.1
Benefits paid	(89.8)	(92.0)
Contributions	10.0	103.4
Fair value of plan assets at end of year	972.5	987.6	885.1
Funded status of the plans	(292.0)	(381.5)
Amounts recognized in the consolidated balance sheets:
Other assets - noncurrent	0.1	0.1
Accrued liabilities - current	(3.3)	(3.3)
Accrued pension and postretirement benefits - noncurrent	(288.8)	(378.3)
Amounts recognized in the consolidated balance sheets	(292.0)	(381.5)
Other Benefits
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	255.1	246.0
Service cost	2.6	3.6	3.3
Interest cost	9.5	9.2	10.4
Benefits paid	(13.0)	(12.7)
Actuarial (gains) loss	(12.7)	(1.7)
Special termination benefits	0.0	0.0
Curtailment gain	0.0	0.0
Plan amendments	0.0	10.7
Projected benefit obligation at end of year	241.5	255.1	246.0
Change in plan assets:
Fair value of plan assets at beginning of year	117.0	115.6
Actual return	10.6	10.9
Benefits paid	(13.0)	(12.7)
Contributions	3.3	3.2
Fair value of plan assets at end of year	117.9	117.0	$ 115.6
Funded status of the plans	(123.6)	(138.1)
Amounts recognized in the consolidated balance sheets:
Other assets - noncurrent	0.0	0.0
Accrued liabilities - current	(15.4)	(15.5)
Accrued pension and postretirement benefits - noncurrent	(108.2)	(122.6)
Amounts recognized in the consolidated balance sheets	$ (123.6)	$ (138.1)

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.