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 amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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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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PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	12 Months Ended
PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property and Equipment
Property and equipment, gross	$ 129,639	$ 115,271
Less: Accumulated depreciation	(100,851)	(88,298)
Property and equipment, net	28,788	26,973
Depreciation expense	15,000	15,900	$ 15,800
Computer and office equipment
Property and Equipment
Property and equipment, gross	32,452	31,371
Software capitalized for internal use
Property and Equipment
Property and equipment, gross	17,625	17,470
Vehicles
Property and Equipment
Property and equipment, gross	2,287	2,379
Medical equipment
Property and Equipment
Property and equipment, gross	42,600	36,230
Work in progress
Property and Equipment
Property and equipment, gross	1,733	2,478
Furniture and fixtures
Property and Equipment
Property and equipment, gross	5,930	5,534
Leasehold improvements
Property and Equipment
Property and equipment, gross	$ 27,012	$ 19,809