Retirement Benefits - Assumptions used to measure benefit obligations (Details) - Pension Plans, Defined Benefit	Jun. 30, 2020	Jun. 30, 2019
U.S. defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.36%	3.28%
Average increase in compensation	2.98%	3.60%
Non-U.S. defined benefit plans | Minimum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	0.20%	0.20%
Average increase in compensation	1.75%	1.75%
Non-U.S. defined benefit plans | Maximum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.03%	2.96%
Average increase in compensation	4.50%	3.90%