Pension and Other Retirement Plans (Schedule of Fair Value and Allocation of Plan Assets) (Details) - Pension Plan [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of plan assets	$ 196,405	$ 171,535	$ 196,597
Cash and money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of plan assets	1,743	7,000
U.S. Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of plan assets	54,258	46,346
International Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of plan assets	29,519	22,783
Domestic Corporate and Government Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of plan assets	60,743	52,179
Domestic Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of plan assets	46,115	38,814
International Corporate and Government Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of plan assets	4,027	4,413
Level I - Fair Value, Inputs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of plan assets	1,743	7,000
Level I - Fair Value, Inputs | Cash and money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of plan assets	1,743	7,000
Level II - Fair Value, Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of plan assets	194,662	164,535
Level II - Fair Value, Inputs [Member] | U.S. Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of plan assets	54,258	46,346
Level II - Fair Value, Inputs [Member] | International Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of plan assets	29,519	22,783
Level II - Fair Value, Inputs [Member] | Domestic Corporate and Government Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of plan assets	60,743	52,179
Level II - Fair Value, Inputs [Member] | Domestic Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of plan assets	46,115	38,814
Level II - Fair Value, Inputs [Member] | International Corporate and Government Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of plan assets	$ 4,027	$ 4,413