Fair Value Measurements (Financial Assets And Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Assets:
Investments in marketable securities	$ 67,483	$ 96,765
Derivatives	471
Total assets	67,954
Liabilities:
Derivatives	3,673
Level 1
Assets:
Investments in marketable securities	38,162
Derivatives	0
Total assets	38,162
Liabilities:
Derivatives	470
Level 2
Assets:
Investments in marketable securities	29,321
Derivatives	471
Total assets	29,792
Liabilities:
Derivatives	3,203
Level 3
Assets:
Investments in marketable securities	0
Derivatives	0
Total assets	0
Liabilities:
Derivatives	$ 0