Long-Lived Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Property and Equipment, Net [Line Items]
Property and equipment	$ 1,324,923	$ 1,193,734
Less accumulated depreciation	(506,034)	(429,845)
Property and equipment, net	818,889	763,889
Land [Member]
Property and Equipment, Net [Line Items]
Property and equipment	37,671	36,511
Buildings And Improvements [Member]
Property and Equipment, Net [Line Items]
Property and equipment	271,302	224,365
Automated Storage And Retrieval Equipment [Member]
Property and Equipment, Net [Line Items]
Property and equipment	139,101	116,127
Equipment And Shelving [Member]
Property and Equipment, Net [Line Items]
Property and equipment	614,528	519,635
Transportation Equipment [Member]
Property and Equipment, Net [Line Items]
Property and equipment	61,429	59,459
Construction In Progress [Member]
Property and Equipment, Net [Line Items]
Property and equipment	$ 200,892	$ 237,637
Minimum [Member] | Buildings And Improvements [Member]
Property and Equipment, Net [Line Items]
Depreciable life in years	15 years
Minimum [Member] | Automated Storage And Retrieval Equipment [Member]
Property and Equipment, Net [Line Items]
Depreciable life in years	5 years
Minimum [Member] | Equipment And Shelving [Member]
Property and Equipment, Net [Line Items]
Depreciable life in years	3 years
Minimum [Member] | Transportation Equipment [Member]
Property and Equipment, Net [Line Items]
Depreciable life in years	3 years
Maximum [Member] | Buildings And Improvements [Member]
Property and Equipment, Net [Line Items]
Depreciable life in years	40 years
Maximum [Member] | Automated Storage And Retrieval Equipment [Member]
Property and Equipment, Net [Line Items]
Depreciable life in years	30 years
Maximum [Member] | Equipment And Shelving [Member]
Property and Equipment, Net [Line Items]
Depreciable life in years	10 years
Maximum [Member] | Transportation Equipment [Member]
Property and Equipment, Net [Line Items]
Depreciable life in years	5 years