Subsequent Events (Details) - HealthCare Royalty Partners IV, L.P. - Royalty Agreement - Subsequent Event $ in Millions	Feb. 25, 2021 USD ($)
Subsequent Event [Line Items]
Annual maximum on royalties and milestones payable	$ 13.0
Maximum on royalties and milestones payable	$ 150.0
Potential revenue subsequent to terms of royalty agreement	85.00%
Proceeds from collaborators	$ 45.0
Potential milestone receivable under terms of royalty agreement	$ 15.0

Collaborative Arrangement, Potential Milestone Receivable

No definition available.

Name:	akba_CollaborativeArrangementPotentialMilestoneReceivable
Namespace Prefix:	akba_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Collaborative Arrangement, Royalty And Milestone Payable, Annual, Maximum

+ References

No definition available.

+ Details

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Namespace Prefix:	akba_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Collaborative Arrangement, Royalty And Milestone Payable , Maximum

+ References

No definition available.

+ Details

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Namespace Prefix:	akba_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Revenue From Contract With Customer, Potential Royalty And Milestones, Subsequent To Collaborative Agreement, Annual, Percentage

+ References

No definition available.

+ Details

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Namespace Prefix:	akba_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Cash received from collaborators during the current period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3536-108585

+ Details

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

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
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Period Type: