Fair Value Measurements (Financial Assets Measured at Fair Value on a Recurring Basis) (Detail) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	$ 35,535,000	$ 13,352,000
Amortized Cost		13,352,000
Business Combination, Contingent Consideration, Liability, Current	4,800,000	2,800,000
Simple Agreements for Future Equity	2,106,000
Business Combination, Contingent Consideration, Liability, Noncurrent		9,800,000
Financial Liabilities Fair Value Disclosure	6,906,000	12,600,000
Cash and Cash Equivalents \| Cash and cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	23,940,000	8,472,000
Amortized Cost	23,940,000	8,472,000
Investment [Domain] \| Equity Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	9,965,000
Restricted cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	1,630,000	4,880,000
Amortized Cost	1,630,000	4,880,000
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	25,570,000	11,972,000
Business Combination, Contingent Consideration, Liability, Current	0	0
Simple Agreements for Future Equity	0
Business Combination, Contingent Consideration, Liability, Noncurrent		0
Financial Liabilities Fair Value Disclosure	0	0
Level 1 \| Cash and Cash Equivalents \| Cash and cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	23,940,000	8,472,000
Level 1 \| Investment [Domain] \| Equity Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	0
Level 1 \| Restricted cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	1,630,000	3,500,000
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	0	1,380,000
Business Combination, Contingent Consideration, Liability, Current	0	0
Simple Agreements for Future Equity	0
Business Combination, Contingent Consideration, Liability, Noncurrent		0
Financial Liabilities Fair Value Disclosure	0	0
Level 2 \| Cash and Cash Equivalents \| Cash and cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	0	0
Level 2 \| Investment [Domain] \| Equity Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	0
Level 2 \| Restricted cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	0	1,380,000
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	9,965,000	0
Business Combination, Contingent Consideration, Liability, Current	4,800,000	2,800,000
Simple Agreements for Future Equity	2,106,000
Business Combination, Contingent Consideration, Liability, Noncurrent		9,800,000
Financial Liabilities Fair Value Disclosure	6,906,000	12,600,000
Level 3 \| Cash and Cash Equivalents \| Cash and cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	0	0
Level 3 \| Investment [Domain] \| Equity Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	9,965,000
Level 3 \| Restricted cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	$ 0	$ 0

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- Definition

Simple Agreements for Future Equity (SAFE Notes)

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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- Definition

Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 25
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6408-128476

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 35
-Paragraph 1
-Subparagraph b
-URI http://asc.fasb.org/extlink&oid=116859824&loc=d3e6819-128478

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Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled beyond one year or the normal operating cycle, if longer.

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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.

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Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

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