Valuation And Qualifying Accounts (Details) - Allowance for Doubtful Accounts [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 747	$ 1,869	$ 1,816
Additions, Charged to Costs and Expenses	6	458	70
Additions, Charged to Other Accounts		(1,422)
Deductions	303	158	17
Balance at End of Period	$ 450	$ 747	$ 1,869