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]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 6,072	$ 7,680	$ 9,386
Charged to costs and expenses	2,427	1,179	1,914
Deductions	1,799	2,787	3,620
Balance at end of period	6,700	6,072	7,680
Tax Valuation Allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	27,230	27,539	30,541
Charged to costs and expenses	0	0	2,239
Deductions	1,251	309	5,241
Balance at end of period	$ 25,979	$ 27,230	$ 27,539