Pension and Other Retirement Plans (Schedule of Net Periodic Pension Benefit) (Details) - Pension Plan - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan Disclosure
Interest cost	$ 1,974	$ 1,796
Expected return on plans' assets	(2,867)	(2,894)
Amortization of actuarial loss	70	168
Net periodic pension benefit	$ (823)	$ (930)