Balance Sheet Information - Property and equipment, net (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property, equipment, and software development, at cost	$ 27,816	$ 28,072
Accumulated depreciation and amortization	(23,677)	(22,982)
Property, equipment, and software development, net	4,139	5,090
Automobiles
Property, Plant and Equipment [Line Items]
Property, equipment, and software development, at cost	13	14
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, equipment, and software development, at cost	178	186
Computer, communications, and network equipment
Property, Plant and Equipment [Line Items]
Property, equipment, and software development, at cost	8,983	9,347
Software
Property, Plant and Equipment [Line Items]
Property, equipment, and software development, at cost	4,028	4,207
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, equipment, and software development, at cost	25	25
Software development
Property, Plant and Equipment [Line Items]
Property, equipment, and software development, at cost	$ 14,589	$ 14,293

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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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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