Pension and Other Postretirement Benefits - Schedule of Fair Values of Pension Plan by Assets Category (Details) - Pension Plans - USD ($) $ in Millions	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 885.1	$ 985.8	$ 1,024.4
Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	15.3	14.9
Domestic and international equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	139.4	158.9
Commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	338.2	393.5
Limited partnerships
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	38.5	38.4
Government agency bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	141.7	143.5
Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	197.3	225.8
Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1.9	1.5
Mortgage/ asset backed securities and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	12.8	9.3
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	196.5	221.2
Level 1 | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Level 1 | Domestic and international equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	139.4	158.9
Level 1 | Commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	54.5	58.6
Level 1 | Limited partnerships
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Level 1 | Government agency bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.7	2.2
Level 1 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Level 1 | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1.9	1.5
Level 1 | Mortgage/ asset backed securities and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	688.6	764.6
Level 2 | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	15.3	14.9
Level 2 | Domestic and international equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Level 2 | Commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	283.7	334.9
Level 2 | Limited partnerships
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	38.5	38.4
Level 2 | Government agency bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	141.0	141.3
Level 2 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	197.3	225.8
Level 2 | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Level 2 | Mortgage/ asset backed securities and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 12.8	$ 9.3