Revenue Recognition and Contracts with Customers (Schedule of Consolidated Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Trade accounts payable and accrued expenses	$ 29,771	$ 33,021	$ 32,422
Deferred revenue from contracts with customers
Deferred taxes			1,402
Retained earnings	368,205	350,423	321,323
Adjustments due ASC 606 [Member]
Trade accounts payable and accrued expenses			(4,000)
Deferred revenue from contracts with customers			6,950
Deferred taxes			(723)
Retained earnings			(2,227)
After Adjustment [Member]
Trade accounts payable and accrued expenses			28,422
Deferred revenue from contracts with customers	$ 9,623	$ 7,477	6,950
Deferred taxes			679
Retained earnings			$ 319,096