Valuation And Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance For Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	$ 426	$ 586	$ 375
Additions	1,010	786	297
Deductions	608	946	86
Balance at end of year	828	426	586
Tax Valuation Allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	11,530	15,936	34,022
Deductions	937	4,406	18,086
Balance at end of year	$ 10,593	$ 11,530	$ 15,936