Valuation And Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Tax Valuation Allowance [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 12,787	$ 15,587	$ 25,979
Charged to costs and expenses	0	0	0
Deductions	7,038	2,800	10,392
Balance at end of period	5,749	12,787	15,587
Allowance For Doubtful Accounts [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 6,855	7,516	6,700
Charged to costs and expenses		2,361	4,255
Deductions		3,022	3,439
Balance at end of period		$ 6,855	$ 7,516