Retirement Plans (Actuarial Assumptions) (Details) - Pension Plan	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
United States
Defined Benefit Plan Disclosure
Discount rate	3.40%	3.90%
Expected rate of return on plan assets	5.90%	5.90%
United Kingdom
Defined Benefit Plan Disclosure
Discount rate	2.80%	2.50%
Expected rate of return on plan assets	3.80%	4.10%