Fair Value of Financial Instruments - Summary of Financial Instruments Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Liabilities
Contingent liability for Essentialis purchase price	$ 9,134	$ 8,835
2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	1	1
Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability	9,135	8,836
Fair Value, Measurements, Recurring [Member] \| Derivative Financial Instruments, Liabilities [Member] \| 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	1	1
Essentialis, Inc. [Member] \| Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	9,134	8,835
Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability	9,135	8,836
Level 3 [Member] \| Fair Value, Measurements, Recurring [Member] \| Derivative Financial Instruments, Liabilities [Member] \| 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	1	1
Level 3 [Member] \| Essentialis, Inc. [Member] \| Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	$ 9,134	$ 8,835

Amount of liability recognized from contingent consideration in asset acquisition, classified as noncurrent.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 50
-Section 15
-Paragraph 3
-URI https://asc.fasb.org/extlink&oid=6911878&loc=d3e8732-128492

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
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Fair value of financial and nonfinancial obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
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