Property, Plant, and Equipment - Components of Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 5,418	$ 5,246
Accumulated depreciation	(4,551)	(4,511)
Property, plant and equipment, net	867	735
Buildings and Land [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	634	589
Enterprise Hardware and Software [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 1,763	1,739
Property, plant and equipment, estimated useful life	3 years
Leaseholds [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 1,787	1,695
Property, plant and equipment, estimated useful life	Lesser of lease term or estimated useful life
Equipment [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 1,032	1,025
Property, plant and equipment, estimated useful life	7 years
Furniture [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 202	$ 198
Property, plant and equipment, estimated useful life	5 years
Buildings [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, estimated useful life	30 years