Revenue Recognition - Schedule of Disaggregated Revenue By Major Product Line in Single Reporting Segment (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Disaggregation Of Revenue [Line Items]
Total	$ 5,227	$ 4,914	$ 5,438	$ 5,613	$ 4,858	$ 8,677	$ 5,587	$ 6,091	$ 21,192	$ 25,213
Service [Member]
Disaggregation Of Revenue [Line Items]
Total	3,144	2,787	3,336	3,507	3,001	2,986	3,253	3,696	12,774	12,936
Subscription Digimarc Guardian [Member]
Disaggregation Of Revenue [Line Items]
Total									3,660	4,165
Subscription Digimarc Discover And Digimarc Barcode [Member]
Disaggregation Of Revenue [Line Items]
Total									2,381	1,354
License [Member]
Disaggregation Of Revenue [Line Items]
Total	$ 596	$ 595	$ 658	$ 528	$ 509	$ 4,385	$ 914	$ 950	$ 2,377	$ 6,758