Retirement Benefits - Pensions, additional information (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Pension Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net pension benefit cost decrease in fiscal period when compared to prior year	$ (122,817)	$ (201,517)	$ (244,574)
Special termination cost	0	0	$ 7,088
Defined Benefit Plan, Expected Amortization, Next Fiscal Year [Abstract]
Estimated amount of net actuarial loss that will be amortized from accumulated other comprehensive (loss) income into net periodic benefit pension cost	114,825
Estimated amount of prior service cost that will be amortized from accumulated other comprehensive (loss) income into net periodic benefit pension cost	6,286
Estimated amount of transition obligation that will be amortized from accumulated other comprehensive (loss) income into net periodic benefit pension cost	18
Accumulated benefit obligation for all defined benefit plans	4,751,111	4,890,058
Defined Benefit Plan, Pension Plan with Project Benefit Obligation in Excess of Plan Assets [Abstract]
Projected benefit obligation for pension plans with accumulated benefit obligations in excess of plan assets	4,933,863	5,120,268
Accumulated benefit obligation for pension plans with accumulated benefit obligations in excess of plan assets	4,665,272	4,805,485
Fair value of plan assets for pension plans with accumulated benefit obligations in excess of plan assets	3,807,859	3,793,696
Projected benefit obligation for pension plans with projected benefit obligations in excess of plan assets	4,970,120	5,142,881
Fair value of plan assets for pension plans with projected benefit obligations in excess of plan assets	3,842,539	3,815,815
Expected cash contributions to defined benefit pension plans in 2019	70,000
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
Estimated future benefit payments in the year ending June 30, 2019	240,163
Estimated future benefit payments in the year ending June 30, 2020	242,051
Estimated future benefit payments in the year ending June 30, 2021	259,402
Estimated future benefit payments in the year ending June 30, 2022	305,553
Estimated future benefit payments in the year ending June 30, 2023	267,258
Estimated future benefit payments in the aggregate for the five years ending June 30, 2024 through June 30, 2028	$ 1,454,646
Change in Assumptions for Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net pension benefit cost decrease in fiscal period when compared to prior year		$ 29,777