Retirement Benefit Plans - Assumptions (Details) - Accrued pension cost	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.50%
Future compensation assumption	2.50%	2.50%	2.50%
Expected long-term return on plan assets	5.22%
Discount rate	2.84%	3.50%	4.36%	3.80%
Future compensation assumption	2.50%	2.50%
U.S. Plans | Minimum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.04%	3.67%	3.75%
Expected long-term return on plan assets	4.50%	5.35%	5.75%
Discount rate	2.71%	3.04%
U.S. Plans | Maximum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.55%	4.43%	3.94%
Expected long-term return on plan assets	6.25%	6.25%	6.50%
Discount rate	2.91%	3.55%
International Plans
Defined Benefit Plan Disclosure [Line Items]
Discount rate		0.75%
International Plans | Minimum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	0.75%	1.50%	1.25%
Future compensation assumption	2.00%	2.00%	2.00%
Expected long-term return on plan assets	1.75%	2.50%	2.50%
Discount rate	0.25%
Future compensation assumption	1.90%	2.00%
International Plans | Maximum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	9.00%	11.00%	9.00%
Future compensation assumption	8.20%	8.23%	8.00%
Expected long-term return on plan assets	9.00%	9.00%	9.00%
Discount rate	7.75%
Future compensation assumption	8.18%	8.20%