Pension and Other Retirement Plans (Schedule of Net Periodic Pension Benefit) (Details) - Pension Plan [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Defined Benefit Plan Disclosure
Interest cost	$ 1,975	$ 1,797	$ 3,949	$ 3,593
Expected return on plans' assets	(2,866)	(2,893)	(5,733)	(5,787)
Amortization of actuarial loss	69	167	139	335
Net periodic pension benefit	$ (822)	$ (929)	$ (1,645)	$ (1,859)