The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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Summary of Significant Accounting Policies - Property, Plant and Equipment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, stated at cost	$ 7,600,949,000	$ 6,251,100,000
Capitalized interest	3,732,000
Capitalization of internal use computer software	29,407,000	25,166,000	$ 16,438,000
Asset retirement obligations	28,256,000	27,757,000
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, stated at cost	400,980,000	314,897,000
Buildings and building improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, stated at cost	2,991,307,000	2,039,902,000
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, stated at cost	770,666,000	592,700,000
Racking
Property, Plant and Equipment [Line Items]
Property, plant and equipment, stated at cost	2,001,831,000	1,996,594,000
Warehouse equipment/vehicles
Property, Plant and Equipment [Line Items]
Property, plant and equipment, stated at cost	481,515,000	467,345,000
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, stated at cost	56,207,000	55,245,000
Computer hardware and software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, stated at cost	680,283,000	627,571,000
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, stated at cost	$ 218,160,000	$ 156,846,000
Minimum \| Buildings and building improvements
Property, Plant and Equipment [Line Items]
Useful life	5 years
Minimum \| Leasehold improvements
Property, Plant and Equipment [Line Items]
Useful life	5 years
Minimum \| Racking
Property, Plant and Equipment [Line Items]
Useful life	1 year
Minimum \| Warehouse equipment/vehicles
Property, Plant and Equipment [Line Items]
Useful life	1 year
Minimum \| Furniture and fixtures
Property, Plant and Equipment [Line Items]
Useful life	1 year
Minimum \| Computer hardware and software
Property, Plant and Equipment [Line Items]
Useful life	2 years
Maximum \| Buildings and building improvements
Property, Plant and Equipment [Line Items]
Useful life	40 years
Maximum \| Leasehold improvements
Property, Plant and Equipment [Line Items]
Useful life	10 years
Maximum \| Racking
Property, Plant and Equipment [Line Items]
Useful life	20 years
Maximum \| Warehouse equipment/vehicles
Property, Plant and Equipment [Line Items]
Useful life	10 years
Maximum \| Furniture and fixtures
Property, Plant and Equipment [Line Items]
Useful life	10 years
Maximum \| Computer hardware and software
Property, Plant and Equipment [Line Items]
Useful life	5 years