Goodwill - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill impairment	$ 0
Goodwill	$ 35,778	$ 35,778	$ 35,778

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
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