Long-Lived Assets (Details) (USD $) In Thousands, unless otherwise specified															12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Land [Member]	Dec. 31, 2011 Land [Member]	Dec. 31, 2012 Buildings And Improvements [Member]	Dec. 31, 2011 Buildings And Improvements [Member]	Dec. 31, 2012 Automated Storage And Retrieval Equipment [Member]	Dec. 31, 2011 Automated Storage And Retrieval Equipment [Member]	Dec. 31, 2012 Equipment And Shelving [Member]	Dec. 31, 2011 Equipment And Shelving [Member]	Dec. 31, 2012 Transportation Equipment [Member]	Dec. 31, 2011 Transportation Equipment [Member]	Dec. 31, 2012 Construction In Progress [Member]	Dec. 31, 2011 Construction In Progress [Member]	Dec. 31, 2012 Minimum [Member] Buildings And Improvements [Member]	Dec. 31, 2012 Minimum [Member] Automated Storage And Retrieval Equipment [Member]	Dec. 31, 2012 Minimum [Member] Equipment And Shelving [Member]	Dec. 31, 2012 Minimum [Member] Transportation Equipment [Member]	Dec. 31, 2012 Maximum [Member] Buildings And Improvements [Member]	Dec. 31, 2012 Maximum [Member] Automated Storage And Retrieval Equipment [Member]	Dec. 31, 2012 Maximum [Member] Equipment And Shelving [Member]	Dec. 31, 2012 Maximum [Member] Transportation Equipment [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment	$ 840,078	$ 725,104	$ 31,831	$ 31,350	$ 200,439	$ 172,372	$ 69,404	$ 61,371	$ 398,240	$ 339,471	$ 52,093	$ 49,074	$ 88,071	$ 71,466
Less accumulated depreciation	(323,651)	(289,503)
Net property and equipment	$ 516,427	$ 435,601
Depreciable life in years															15 years	5 years	3 years	3 years	40 years	30 years	10 years	5 years