The Company and a Summary of its Significant Accounting Policies - Summary of Percentages of Total Revenue or Accounts Receivable for Third Party Payers and Pharmaceutical Customers (Details) - Customer Concentration Risk
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12 Months Ended |
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
| Assay Revenue Payor A | Total Revenue |
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| Product Information [Line Items] |
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| Concentration risk, percentage |
36.00%
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32.00%
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| Assay Revenue Payor A | Accounts Receivable |
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| Product Information [Line Items] |
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| Concentration risk, percentage |
23.00%
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21.00%
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| Assay Revenue Payor B | Total Revenue |
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| Product Information [Line Items] |
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| Concentration risk, percentage |
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11.00%
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12.00%
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| Assay Revenue Payor B | Accounts Receivable |
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| Product Information [Line Items] |
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| Concentration risk, percentage |
15.00%
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| Contract Revenue Customer A | Total Revenue |
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| Product Information [Line Items] |
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| Concentration risk, percentage |
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23.00%
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22.00%
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| Contract Revenue Customer B | Accounts Receivable |
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| Product Information [Line Items] |
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| Concentration risk, percentage |
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17.00%
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| Contract Revenue Customer C | Total Revenue |
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| Product Information [Line Items] |
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| Concentration risk, percentage |
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29.00%
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