Summary Of Significant Accounting Policies Summary of Significant Accounting Policies (Allowance for Doubtful Accounts) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Accounts Receivable, Allowance for Credit Loss, Current	$ 2,419	$ 5,233	$ 5,132	$ 5,026
Accounts Receivable, Credit Loss Expense (Reversal)	460	3,917	5,317
Accounts Receivable, Allowance for Credit Loss, Writeoff	$ (3,274)	$ (3,816)	$ (5,211)