Name:	akba_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesFairValueOfOffMarketElement
Namespace Prefix:	akba_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Commitments and contingencies.

No definition available.

Name:	akba_CommitmentsAndContingenciesLineItems
Namespace Prefix:	akba_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Cost of purchased minimum quantity product.

No definition available.

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

Excess Inventory Purchase Commitments Expense (Reversal)

No definition available.

Name:	akba_ExcessInventoryPurchaseCommitmentsExpenseReversal
Namespace Prefix:	akba_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Lessee leasing arrangements, operating leases, number of lease period extension options.

No definition available.

Name:	akba_LesseeLeasingArrangementsOperatingLeasesNumberOfLeasePeriodExtensionOptions
Namespace Prefix:	akba_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Long-Term Purchase Commitment, Fixed Price, Period

No definition available.

Name:	akba_LongTermPurchaseCommitmentFixedPricePeriod
Namespace Prefix:	akba_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Long-Term Purchase Commitment, Option To Extend, Prior Notice Period

No definition available.

Name:	akba_LongTermPurchaseCommitmentOptionToExtendPriorNoticePeriod
Namespace Prefix:	akba_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Long-Term Purchase Commitment, Option To Terminate, Prior Notice Period

No definition available.

Name:	akba_LongTermPurchaseCommitmentOptionToTerminatePriorNoticePeriod
Namespace Prefix:	akba_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Long-Term Purchase Commitment, Termination Amount Payable

No definition available.

Name:	akba_LongTermPurchaseCommitmentTerminationAmountPayable
Namespace Prefix:	akba_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Long-Term Purchase Commitment, Termination Amount Payable, After Upfront Payment

No definition available.

Name:	akba_LongTermPurchaseCommitmentTerminationAmountPayableAfterUpfrontPayment
Namespace Prefix:	akba_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Long-Term Purchase Commitment, Termination Amount Payable, After Upfront Payment, Number Of Quarterly Payments

No definition available.

Name:	akba_LongTermPurchaseCommitmentTerminationAmountPayableAfterUpfrontPaymentNumberOfQuarterlyPayments
Namespace Prefix:	akba_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Long-Term Purchase Commitment, Termination Amount Payable, After Upfront Payment, Per Quarter

No definition available.

Name:	akba_LongTermPurchaseCommitmentTerminationAmountPayableAfterUpfrontPaymentPerQuarter
Namespace Prefix:	akba_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Long-Term Purchase Commitment, Termination Amount Payable, Imputed Interest

No definition available.

Name:	akba_LongTermPurchaseCommitmentTerminationAmountPayableImputedInterest
Namespace Prefix:	akba_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Long-Term Purchase Commitment, Upfront Payment Termination Amount

No definition available.

Name:	akba_LongTermPurchaseCommitmentUpfrontPaymentTerminationAmount
Namespace Prefix:	akba_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Long-Term Purchase Commitment, Upfront Termination Amount, Cost Of Goods Sold

No definition available.

Name:	akba_LongTermPurchaseCommitmentUpfrontTerminationAmountCostOfGoodsSold
Namespace Prefix:	akba_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Operating Lease, Annual Rent Escalation, Percentage

No definition available.

Name:	akba_OperatingLeaseAnnualRentEscalationPercentage
Namespace Prefix:	akba_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Operating Lease, Annual Rent Expense

No definition available.

Name:	akba_OperatingLeaseAnnualRentExpense
Namespace Prefix:	akba_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Operating Lease, Free Monthly Rent, Period

No definition available.

Name:	akba_OperatingLeaseFreeMonthlyRentPeriod
Namespace Prefix:	akba_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Operating Lease, Monthly Rent Expense

No definition available.

Name:	akba_OperatingLeaseMonthlyRentExpense
Namespace Prefix:	akba_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Purchase Commitment, Option For Non-Auto Renewal, Prior Written Notice Period

No definition available.

Name:	akba_PurchaseCommitmentOptionForNonAutoRenewalPriorWrittenNoticePeriod
Namespace Prefix:	akba_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Purchase Commitment, Renewal Term

No definition available.

Name:	akba_PurchaseCommitmentRenewalTerm
Namespace Prefix:	akba_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Area of a real estate property.

No definition available.

Name:	us-gaap_AreaOfRealEstateProperty
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

Amount of incentive granted by lessor to lessee.

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 25
-Paragraph 6
-URI https://asc.fasb.org/extlink&oid=123415192&loc=d3e40010-112707

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 25
-Paragraph 7
-URI https://asc.fasb.org/extlink&oid=123415192&loc=d3e40019-112707

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 10
-Section 30
-Paragraph 5
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123388062&loc=SL77916639-209961

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

Remaining lease term of operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI https://asc.fasb.org/extlink&oid=128292326&loc=SL77918673-209980

Name:	us-gaap_LesseeOperatingLeaseRemainingLeaseTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI https://asc.fasb.org/extlink&oid=128292326&loc=SL77918673-209980

Name:	us-gaap_LesseeOperatingLeaseRenewalTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

The minimum amount the entity agreed to spend under the long-term purchase commitment.

No definition available.

Name:	us-gaap_LongTermPurchaseCommitmentAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Period covered by the long-term purchase commitment, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_LongtermPurchaseCommitmentPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI https://asc.fasb.org/extlink&oid=123414884&loc=SL77918982-209971

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=128292326&loc=SL77918686-209980

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

Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 5
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=123391704&loc=SL77918643-209977

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(1)
-URI https://asc.fasb.org/extlink&oid=128292326&loc=SL77918686-209980

Name:	us-gaap_OperatingLeasePayments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Weighted average discount rate for operating lease calculated at point in time.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(4)
-URI https://asc.fasb.org/extlink&oid=128292326&loc=SL77918686-209980

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI https://asc.fasb.org/extlink&oid=123414884&loc=SL77918982-209971

Name:	us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Minimum amount to be expended to satisfy the terms of arrangements in which the entity has agreed to expend funds to procure goods or services, excluding long-term purchase commitments or unconditional purchase obligations.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(17))
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(19))
-URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(25))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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

The amount of costs incurred under a research and development arrangement accounted for as a contract to perform research and development for others.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 20
-Section 50
-Paragraph 3
-URI https://asc.fasb.org/extlink&oid=6420387&loc=d3e23221-108380

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=6420387&loc=d3e23199-108380

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

The amount of an asset, typically cash, provided to a counterparty to provide certain assurance of performance by the entity pursuant to the terms of a written or oral agreement, such as a lease.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(17))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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

Amount of sublease income excluding finance and operating lease expense.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (e)
-URI https://asc.fasb.org/extlink&oid=128292326&loc=SL77918686-209980

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI https://asc.fasb.org/extlink&oid=123414884&loc=SL77918982-209971

Name:	us-gaap_SubleaseIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Name:	us-gaap_PurchaseCommitmentExcludingLongtermCommitmentAxis=akba_SupplyAgreementPatheonIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_BusinessAcquisitionAxis=akba_KeryxBiopharmaceuticalsIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_StatementGeographicalAxis=akba_CambridgeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_CounterpartyNameAxis=akba_BioVectraIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_CounterpartyNameAxis=akba_SiegfriedEvionnazSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_CounterpartyNameAxis=akba_STAPharmaceuticalHongKongLimitedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_CounterpartyNameAxis=akba_WuXiSTAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_OtherCurrentAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=akba_OfficeSpaceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_StatementGeographicalAxis=akba_BostonMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: