Valuation And Qualifying Accounts (Details) - Allowance for Doubtful Accounts [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 1,796	$ 1,319	$ 938
Additions, Charged to Costs and Expenses	1	516	488
Additions, Charged to Other Accounts			19
Deductions	(19)	39	126
Balance at End of Period	$ 1,816	$ 1,796	$ 1,319