SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Balances Related to Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 124,200	$ 124,900
Less accumulated depreciation	(96,137)	(95,472)
Property and equipment, net	28,113	29,449
Building and Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	8,700	8,700
Equipment and Furniture [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	55,600	53,400
Finance Leases [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	5,200	2,900
Computer Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 54,700	$ 59,900

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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-SubTopic 10
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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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