Pension and Other Retirement Plans (Schedule of Net Periodic Pension Benefit) (Details) - Pension Plan - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure
Interest cost	$ 1,973	$ 1,796	$ 5,922	$ 5,389
Expected return on plans' assets	(2,866)	(2,894)	(8,599)	(8,681)
Amortization of actuarial loss	70	168	209	503
Net periodic pension benefit	$ (823)	$ (930)	$ (2,468)	$ (2,789)