Income Taxes (Schedule Of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Abstract]
Computed expected tax expense	$ 17,271	$ 12,627	$ 18,229
Foreign tax differential	(17,383)	(11,648)	(16,384)
State rate changes	(3,136)
State income tax expense, net of federal income tax benefit	(234)	433	534
Subpart F income	4,630	3,592	2,202
Change in valuation allowance	675
IRC Section 162(m) excess officer's compensation	63	215	172
Non-deductible stock-based compensation	63	94	133
Excess tax benefit related to stock-based compensation	(176)	(155)	(34)
Increase in uncertain tax positions	39	1	1
Adjustment for prior years	(57)	(13)	304
Other	45	(363)	(68)
Total income tax expense (benefit)	$ 1,800	$ 4,783	$ 5,089