Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Insurance and claims accruals	$ 76,596	$ 73,211
Allowance for uncollectible accounts	5,672	7,813
Other	8,437	9,416
Gross deferred tax assets	90,705	90,440
Property and equipment	282,642	288,032
Prepaid expenses	6,906	6,774
Other	3,079	3,026
Gross deferred tax liabilities	292,627	297,832
Net deferred tax liability	$ 201,922	$ 207,392