Retirement Benefits - Net periodic pension cost recognized (Details) - Pension Plans, Defined Benefit - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 94,356	$ 94,650	$ 97,960
Interest cost	126,131	181,469	176,556
Special termination cost	0	7,088	21,174
Settlement cost	0	5,102	0
Expected return on plan assets	(239,537)	(221,629)	(218,938)
Amortization of prior service cost	8,116	7,470	9,437
Amortization of unrecognized actuarial loss	212,433	170,407	152,664
Amortization of initial net obligation	18	17	17
Net periodic benefit cost	$ 201,517	$ 244,574	$ 238,870