Nature Of Operations And Accounting Policies (Schedule Of Intangible Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-lived Intangible Assets [Roll Forward]
Intangible assets, beginning balance	$ 37,047	$ 37,047
Acquired intangible assets	3,078	0
Foreign currency translation	111
Intangible assets, ending balance	40,236	37,047	$ 37,047
Changes in Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	(16,051)	(12,496)
Amortization expense	(4,062)	(3,555)	(4,700)
Accumulated amortization, ending balance	$ (20,113)	(16,051)	(12,496)
Weighted average remaining contractual life, in years	5 years 10 months 24 days
Trademark/ Tradenames
Finite-lived Intangible Assets [Roll Forward]
Intangible assets, beginning balance	$ 3,324	3,324
Acquired intangible assets	0	0
Foreign currency translation	0
Intangible assets, ending balance	3,324	3,324	3,324
Changes in Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	(2,644)	(2,312)
Amortization expense	(332)	(332)
Accumulated amortization, ending balance	$ (2,976)	(2,644)	(2,312)
Weighted average remaining contractual life, in years	1 year
Customer Relationships
Finite-lived Intangible Assets [Roll Forward]
Intangible assets, beginning balance	$ 15,365	15,365
Acquired intangible assets	3,078	0
Foreign currency translation	111
Intangible assets, ending balance	18,554	15,365	15,365
Changes in Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	(7,710)	(6,428)
Amortization expense	(1,789)	(1,282)
Accumulated amortization, ending balance	$ (9,499)	(7,710)	(6,428)
Weighted average remaining contractual life, in years	5 years 8 months 12 days
Acquired Contractual Rights
Finite-lived Intangible Assets [Roll Forward]
Intangible assets, beginning balance	$ 18,358	18,358
Acquired intangible assets	0	0
Foreign currency translation	0
Intangible assets, ending balance	18,358	18,358	18,358
Changes in Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	(5,697)	(3,756)
Amortization expense	(1,941)	(1,941)
Accumulated amortization, ending balance	$ (7,638)	$ (5,697)	$ (3,756)
Weighted average remaining contractual life, in years	6 years 2 months 12 days