Pension and Other Retirement Plans (Schedule of Net Periodic Pension Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Pension and Other Retirement Plans [Abstract]
Interest cost	$ 7,896	$ 7,185
Expected return on plans' assets	(11,464)	(11,575)
Amortization of actuarial loss	278	671
Net periodic pension benefit	$ (3,290)	$ (3,719)