Revenues - Summary of Disaggregation of Accounts Receivable on the Basis of Customers (Detail) - USD ($) $ in Thousands |
Sep. 30, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
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| Diaggregation Of Accounts Receivable On The Basis Of Customers [Line Items] | |||
| Allowance for doubtful accounts | $ 0 | $ 0 | $ 0 |
| Total accounts receivable | 4,909 | 2,903 | 4,328 |
| US Federal Government and Agencies [Member] | |||
| Diaggregation Of Accounts Receivable On The Basis Of Customers [Line Items] | |||
| Accounts receivable, Before allowance for doubtful accounts | 4,584 | 1,335 | 3,349 |
| Commercial and Other [Member] | |||
| Diaggregation Of Accounts Receivable On The Basis Of Customers [Line Items] | |||
| Accounts receivable, Before allowance for doubtful accounts | $ 325 | $ 1,568 | $ 979 |
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- Definition Diaggregation Of Accounts Receivable On The Basis Of Customers. No definition available.
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- Definition Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of allowance for credit loss on accounts receivable, classified as current. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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