Retirement Benefit Plans (Weighted Average Asset Allocations) (Details) - Pension Plans, Defined Benefit	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Asset allocations as a percentage of plan assets	100.00%	100.00%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Asset allocations as a percentage of plan assets	55.00%	55.00%
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Asset allocations as a percentage of plan assets	38.00%	38.00%
Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Asset allocations as a percentage of plan assets	2.00%	2.00%
Other
Defined Benefit Plan Disclosure [Line Items]
Asset allocations as a percentage of plan assets	5.00%	5.00%