Retirement Benefit Plans (Fair Value Hierarchy) (Details) - Pension Plan - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair value of each major category of U.S. plan assets	$ 34,954	$ 38,527	$ 34,628
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of each major category of U.S. plan assets	34,954	38,527
Level 1 | U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of each major category of U.S. plan assets	14,834	18,175
Level 1 | Non-U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of each major category of U.S. plan assets	6,790	8,120
Level 1 | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of each major category of U.S. plan assets	13,169	12,097
Level 1 | Money market
Defined Benefit Plan Disclosure [Line Items]
Fair value of each major category of U.S. plan assets	$ 161	$ 135