Income Taxes (Summary Of Temporary Differences That Give Rise To Deferred Income Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Inventory costing and valuation methods	$ 4,556	$ 4,311
Allowance for doubtful accounts receivable	4,529	4,873
Insurance claims payable	10,930	10,404
Promotions payable	1,738	1,586
Stock-based compensation	8,270	7,837
Federal and state benefit of uncertain tax positions	1,911	1,327
Foreign net operating loss and credit carryforwards	5,155	5,768
Foreign valuation allowances	(3,406)	(3,007)
Other, net	1,541	592
Total deferred income tax assets	35,224	33,691
Property and equipment	(90,281)	(80,458)
Total deferred income tax liabilities	(90,281)	(80,458)
Net deferred income tax liabilities	$ (55,057)	$ (46,767)