Revenue Recognition (Details) - Disaggregation of revenue from contracts with customers - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Digital product sales:
Revenue from contracts with customers	$ 3,747	$ 3,062	$ 7,346	$ 7,597
Digital Product Sales [Member]
Digital product sales:
Revenue from contracts with customers	3,113	2,353	6,204	6,301
Digital Product Lease And Maintenance [Member]
Digital product sales:
Revenue from contracts with customers	634	709	1,142	1,296
Catalog And Small Customized Products [Member] | Digital Product Sales [Member]
Digital product sales:
Revenue from contracts with customers	3,113	2,353	6,204	5,301
Large Customized Products [Member] | Digital Product Sales [Member]
Digital product sales:
Revenue from contracts with customers				1,000
Operating Leases [Member] | Digital Product Lease And Maintenance [Member]
Digital product sales:
Revenue from contracts with customers	338	439	630	766
Maintenance Agreements [Member] | Digital Product Lease And Maintenance [Member]
Digital product sales:
Revenue from contracts with customers	$ 296	$ 270	$ 512	$ 530