Valuation And Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance Beginning of Year	$ 2,390	$ 2,989	$ 1,307
Charges (Credits) to Cost and Expenses	2,067	(175)	2,774
Deductions	(976)	(424)	(1,092)
Balance End of Year	$ 3,481	$ 2,390	$ 2,989