SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS [Schedule] (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 799	$ 860	$ 986
Additions Charged to Costs/Expenses (Recoveries)	72	226	178
Deductions	187	287	304
Balance at End of Period	684	799	860
Valuation Allowance of Deferred Tax Assets [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	156,342	159,298	158,851
Additions Charged to Costs/Expenses (Recoveries)	(46,183)	(5,045)	447
Deductions	0	(2,089)	0
Balance at End of Period	$ 110,159	$ 156,342	$ 159,298