Fair Value Measurements (Schedule of Assets and Liabilities Measured at a Fair Value on Recurring Basis) (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments related to deferred compensation liabilities	$ 948,000	$ 823,000
Interest rate swaps asset		136,000
Recurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments related to deferred compensation liabilities	948,000	823,000
Deferred compensation liabilities	952,000	824,000
Interest rate swaps liability	18,927,000	7,180,000
Interest rate swaps asset		136,000
Recurring Basis [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments related to deferred compensation liabilities	948,000	823,000
Deferred compensation liabilities	952,000	824,000
Recurring Basis [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps liability	$ 18,927,000	7,180,000
Interest rate swaps asset		$ 136,000