Commitments And Contingencies (Changes in Self-insurance Liability) (Details) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Write-off of insurance receivables	-9297	-5326	-15000	29624
Litigation of Recorded Insurance Receivable				$ 71,600
Insurance Settlements Receivable	$ 213,407			213,407	$ 307,344
Insurance Related Expenses [Roll Forward]
Balance, beginning of period			$ 831,058	831,058	924,563	$ 995,692
Reserves provided				81,503	97,916	80,860
Increase (Decrease) in Liability for Claims and Claims Adjustment Expense Reserve				(97,789)	(57,132)	(64,775)
Payments				(55,960)	(134,289)	(87,214)
Balance, end of period	$ 758,812			$ 758,812	$ 831,058	924,563
Loss Contingency, Receivable, Period Increase (Decrease)						$ 32,600