Related Party Transactions (Details)	9 Months Ended
Sep. 30, 2021 mi
Affiliated Entity
Related Party Transactions
Harness racing track length (in miles)	0.625
Motorsports superspeedway length (in miles)	1
Period for set up and tear down rights	14 days
Board of Directors Chairman
Related Party Transactions
Voting rights (in percent)	50.00%

Represents the length of harness racing track used by the related party of the entity.

No definition available.

Name:	dvd_LengthOfHarnessRacingTrackUsedByRelatedParty
Namespace Prefix:	dvd_
Data Type:	num:lengthItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the length of the motorsports superspeedway racing track.

+ References

No definition available.

+ Details

Name:	dvd_LengthOfMotorsportsSuperspeedwayRacingTrack
Namespace Prefix:	dvd_
Data Type:	num:lengthItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the period, before and after the period of exclusive use of harness track, for which the related party has set up and tear down rights.

+ References

No definition available.

+ Details

Name:	dvd_PeriodOfSetUpAndTearDownRightsPertainingToHarnessTrackToRelatedParty
Namespace Prefix:	dvd_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=srt_AffiliatedEntityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=srt_BoardOfDirectorsChairmanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: