Research collaboration agreement with Allergan (Details) $ in Thousands	12 Months Ended
Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jul. 24, 2015 USD ($) Option
Research collaboration agreement with Allergan
Research and development	$ 44,330	$ 48,788
Non-Refundable Milestone Payment		1,000
RCA
Research collaboration agreement with Allergan
Payment of option exercise fee			$ 1,000
Number of options to acquire molecules \| Option			3
capitalized contract costs	0
Research and development	$ 7,300	$ 7,900
Development activities reimbursement percentage	50.00%	50.00%
Development activities expenses reimbursed	$ 3,700	$ 3,900
Remaining performance obligation		$ 0

Amount of expenses paid towards non-refundable milestone payment.

No definition available.

Name:	aptx_NonRefundableMilestonePayment
Namespace Prefix:	aptx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of options to acquire molecules from a pool of eligible compounds that would result in the termination of the research collaboration agreement.

+ References

No definition available.

+ Details

Name:	aptx_NumberOfOptionsToAcquireMolecules
Namespace Prefix:	aptx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

It represents payment for option exercise fee.

+ References

No definition available.

+ Details

Name:	aptx_PaymentOfOptionExerciseFee
Namespace Prefix:	aptx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount that was reimbursed under the research collaboration agreement.

+ References

No definition available.

+ Details

Name:	aptx_ResearchAndDevelopmentExpenseReimbursementAmount
Namespace Prefix:	aptx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The percentage of research and development expenses that are reimbursable under the research collaboration agreement.

+ References

No definition available.

+ Details

Name:	aptx_ResearchAndDevelopmentExpenseReimbursementPercentage
Namespace Prefix:	aptx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization and accumulated impairment loss, of asset recognized from cost incurred to obtain or fulfill contract with customer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=68051541&loc=SL49131252-203054

+ Details

Name:	us-gaap_CapitalizedContractCostNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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.

+ References

No definition available.

+ Details

Name:	us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6420194&loc=d3e21568-108373

+ Details

Name:	us-gaap_ResearchAndDevelopmentExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130556-203045

+ Details

Name:	us-gaap_RevenueRemainingPerformanceObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_TypeOfArrangementAxis=aptx_RcaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: