Fair Value Measurements (Financial Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets:
Investments in marketable securities	$ 96,765	$ 135,667
Derivatives	853	5,857
Total assets	97,618	141,524
Liabilities:
Derivatives	3,899	3,065
Level 1
Assets:
Investments in marketable securities	57,224	35,029
Derivatives	21	5,269
Total assets	57,245	40,298
Liabilities:
Derivatives	7	0
Level 2
Assets:
Investments in marketable securities	39,541	100,638
Derivatives	832	527
Total assets	40,373	101,165
Liabilities:
Derivatives	3,892	3,065
Level 3
Assets:
Investments in marketable securities	0	0
Derivatives	0	61
Total assets	0	61
Liabilities:
Derivatives	$ 0	$ 0