Stock-Based Compensation - Schedule of Unvested Performance Restricted Stock Unit (Detail))(Parenthetical) - Performance Restricted Stock Units [Member] - $ / shares shares in Thousands	3 Months Ended	9 Months Ended
Jun. 30, 2021	Sep. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock cancelled and reissued	21	21
Grant date fair value		$ 28.93

Share based compensation arrangement by share based payment award equity instruments other than options reissued in period grant date fair value.

No definition available.

Name:	dmrc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsReissuedInPeriodGrantDateFairValue
Namespace Prefix:	dmrc_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration