Summary of Significant Accounting Policies - Schedule of Intangible Assets (Detail) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Investments In Loans [Line Items]
Intangibles assets	$ 50,007,000	$ 51,090,000
Intellectual Property [Member]
Investments In Loans [Line Items]
Intangibles assets	18,150,000	18,974,000
Contractor Relationships [Member]
Investments In Loans [Line Items]
Intangibles assets	5,692,000	5,951,000
Race Organization [Member]
Investments In Loans [Line Items]
Intangibles assets	$ 26,165,000	$ 26,165,000

Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph ((a)(1),(b))
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16212-109274

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant