Fair Value Measurements (Financial Assets Measured at Fair Value on a Recurring Basis) (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	$ 17,875	$ 13,352
Amortized Cost	17,875	13,352
Accrued royalties, fulfillment and other current liabilities, Napster acquisition contingent consideration	12,400	2,800
Simple Agreements for Future Equity	2,106
Total liabilities	14,506	12,600
Cash and Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value		8,472
Amortized Cost		8,472
Cash and Cash Equivalents \| Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	13,245	8,472
Amortized Cost	13,245	8,472
Cash and Cash Equivalents \| Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value		0
Amortized Cost		0
Restricted cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	4,630	4,880
Amortized Cost	4,630	4,880
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	16,745	11,972
Simple Agreements for Future Equity	0
Total liabilities	0	0
Level 1 \| Cash and Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value		8,472
Level 1 \| Cash and Cash Equivalents \| Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	13,245	8,472
Level 1 \| Cash and Cash Equivalents \| Money market funds
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	3,500	3,500
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	1,130	1,380
Simple Agreements for Future Equity	0
Total liabilities	0	0
Level 2 \| Cash and Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value		0
Level 2 \| Cash and Cash Equivalents \| Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	0	0
Level 2 \| Cash and Cash Equivalents \| Money market funds
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	1,130	1,380
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	0	0
Simple Agreements for Future Equity	2,106
Total liabilities	14,506	12,600
Level 3 \| Cash and Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value		0
Level 3 \| Cash and Cash Equivalents \| Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	0	0
Level 3 \| Cash and Cash Equivalents \| Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value		0
Level 3 \| Restricted cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	0	0
Napster
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accrued royalties, fulfillment and other current liabilities, Napster acquisition contingent consideration	12,400	2,800
Napster acquisition contingent consideration		9,800
Napster \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accrued royalties, fulfillment and other current liabilities, Napster acquisition contingent consideration	0	0
Napster acquisition contingent consideration		0
Napster \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accrued royalties, fulfillment and other current liabilities, Napster acquisition contingent consideration	0	0
Napster acquisition contingent consideration		0
Napster \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accrued royalties, fulfillment and other current liabilities, Napster acquisition contingent consideration	$ 12,400	2,800
Napster acquisition contingent consideration		$ 9,800

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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)
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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

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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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Fair value of obligations not classified as financial liabilities. Includes, but is not limited to, accounts payable and accrued liabilities, commitments, obligations, and other liabilities.

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