Fair Value Measurements (Financial Assets Measured at Fair Value on a Recurring Basis) (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	$ 24,338	$ 35,535
Accrued royalties, fulfillment and other current liabilities, Napster acquisition contingent consideration	3,127	3,373
Future Issuance Of Equity, Liability	2,106	2,106
Nonfinancial Liabilities Fair Value Disclosure	5,866	6,906
Cash and Cash Equivalents \| Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	17,015	23,940
Amortized Cost	17,015	23,940
Securities Investment [Member] \| Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	5,693	9,965
Restricted Cash Equivalents And Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	1,630	1,630
Amortized Cost	1,630	1,630
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	18,645	25,570
Future Issuance Of Equity, Liability	0	0
Nonfinancial Liabilities Fair Value Disclosure	0	0
Level 1 \| Cash and Cash Equivalents \| Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	17,015	23,940
Level 1 \| Securities Investment [Member] \| Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	0	0
Level 1 \| Restricted Cash Equivalents And Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	1,630	1,630
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	0	0
Future Issuance Of Equity, Liability	0	0
Nonfinancial Liabilities Fair Value Disclosure	0	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 \| Securities Investment [Member] \| Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	0	0
Level 2 \| Restricted Cash Equivalents And Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	0	0
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	5,693	9,965
Future Issuance Of Equity, Liability	2,106	2,106
Nonfinancial Liabilities Fair Value Disclosure	5,866	6,906
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 \| Securities Investment [Member] \| Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial assets fair value	5,693	9,965
Level 3 \| Restricted Cash Equivalents And Investments [Member]
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	3,760	4,800
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 \| 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 \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accrued royalties, fulfillment and other current liabilities, Napster acquisition contingent consideration	$ 3,760	$ 4,800

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+ 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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-Publisher FASB
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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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