Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Property and Equipment, net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2019	Dec. 31, 2018
Property and equipment, net
Property and equipment, gross	$ 949,096		$ 949,096			$ 897,141
Less accumulated depreciation and amortization	(402,040)		(402,040)			(290,164)
Property and equipment, net	547,056		547,056		$ 379,268	606,977
Depreciation and amortization	50,100	$ 32,400	133,800	$ 86,600
Furniture and computer equipment
Property and equipment, net
Property and equipment, gross	459,896		459,896			339,761
Site and software development costs
Property and equipment, net
Property and equipment, gross	263,555		263,555			172,653
Leasehold improvements
Property and equipment, net
Property and equipment, gross	189,622		189,622			109,929
Construction in progress
Property and equipment, net
Property and equipment, gross	36,023		36,023			90,104
Buildings
Property and equipment, net
Property and equipment, gross	$ 0		$ 0			$ 184,694