| Acquisitions - Pro Forma Financial Information (Details) - Culture Kings - USD ($) $ / shares in Units, $ in Thousands | 3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
| Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | |
| Business Acquisition [Line Items] | ||||
| Net sales | $ 161,762 | $ 112,049 | $ 430,967 | $ 257,613 | 
| Net income attributable to a.k.a. Brands Holding Corp. | $ 2,278 | $ 9,670 | $ 12,084 | $ 1,355 | 
| Net income per share, basic (in dollars per share) | $ 0.03 | $ 0.11 | $ 0.14 | $ 0.02 | 
| Net income per share, diluted (in dollars per share) | $ 0.03 | $ 0.11 | $ 0.14 | $ 0.02 | 
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- 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. No definition available. 
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- Definition The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef 
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- Definition The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef 
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- Definition The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Details 
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