Retirement Benefits - Assumptions used to measure benefit obligations (Details) - Pension Plans, Defined Benefit	Jun. 30, 2019	Jun. 30, 2018
U.S. defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.28%	4.01%
Average increase in compensation	3.60%	3.65%
Non-U.S. defined benefit plans | Minimum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	0.20%	0.30%
Average increase in compensation	1.75%	1.75%
Non-U.S. defined benefit plans | Maximum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.96%	3.37%
Average increase in compensation	3.90%	5.50%