Fair Value Measurements (Financial Assets and Liabilities Measured at Fair Value) (Details) - Recurring - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Marketable securities
Assets
Total assets	$ 6,024	$ 14,409
Interest Rate Swap
Liabilities:
Total liabilities	667
Level 1 | Marketable securities
Assets
Total assets	6,024	14,409
Level 1 | Interest Rate Swap
Liabilities:
Total liabilities	0
Level 2 | Marketable securities
Assets
Total assets	0	0
Level 2 | Interest Rate Swap
Liabilities:
Total liabilities	667
Level 3 | Marketable securities
Assets
Total assets	0	$ 0
Level 3 | Interest Rate Swap
Liabilities:
Total liabilities	$ 0