Retirement Benefits - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
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	$ (201,517)	$ (244,574)	$ (238,870)
Special termination cost	0	7,088	21,174
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) 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	141,399
Estimated amount of prior service cost that will be amortized from accumulated other comprehensive (loss) income into net periodic benefit pension cost	6,055
Estimated amount of transition asset that will be amortized from accumulated other comprehensive (loss) income into net periodic benefit pension cost	17
Accumulated benefit obligation for all defined benefit plans	4,890,058	4,884,985
Defined Benefit Plan, Plans with Benefit Obligations in Excess of Plan Assets [Abstract]
Projected benefit obligation for pension plans with accumulated benefit obligations in excess of plan assets	5,120,268	5,211,768
Accumulated benefit obligation for pension plans with accumulated benefit obligations in excess of plan assets	4,805,485	4,796,860
Fair value of plan assets for pension plans with accumulated benefit obligations in excess of plan assets	3,793,696	3,206,287
Projected benefit obligation for pension plans with projected benefit obligations in excess of plan assets	5,142,881	5,310,979
Fair value of plan assets for pension plans with projected benefit obligations in excess of plan assets	3,815,815	3,302,370
Expected cash contributions to defined benefit pension plans in 2018	68,000
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
Estimated future benefit payments in the year ending June 30, 2018	231,732
Estimated future benefit payments in the year ending June 30, 2019	236,968
Estimated future benefit payments in the year ending June 30, 2020	243,956
Estimated future benefit payments in the year ending June 30, 2021	260,645
Estimated future benefit payments in the year ending June 30, 2022	296,949
Estimated future benefit payments in the aggregate for the five years ending June 30, 2023 through June 30, 2027	1,448,318
Other Postretirement Benefit 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	(4,357)	(8,754)	$ (4,340)
Special termination cost	0	$ 4,521
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) 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	1,095
Estimated amount of prior service cost that will be amortized from accumulated other comprehensive (loss) income into net periodic benefit pension cost	(121)
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
Estimated future benefit payments in the year ending June 30, 2018	6,532
Estimated future benefit payments in the year ending June 30, 2019	6,426
Estimated future benefit payments in the year ending June 30, 2020	6,034
Estimated future benefit payments in the year ending June 30, 2021	5,870
Estimated future benefit payments in the year ending June 30, 2022	5,629
Estimated future benefit payments in the aggregate for the five years ending June 30, 2023 through June 30, 2027	25,142
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