Retirement Benefits - Net periodic pension cost recognized (Details) - Pension Plans, Defined Benefit - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 76,647	$ 82,993	$ 94,356
Interest cost	160,542	144,339	126,131
Expected return on plan assets	(251,072)	(258,490)	(239,537)
Amortization of prior service cost	6,655	6,570	8,116
Amortization of unrecognized actuarial loss	121,823	147,387	212,433
Amortization of transition obligation	18	18	18
Net periodic benefit cost	$ 114,613	$ 122,817	$ 201,517