Product Revenue and Reserves for Variable Consideration - Product Revenue Allowance and Reserve Categories (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 31,543	$ 23,737
Current provisions related to sales in current year	119,438	80,876
Adjustments related to prior year sales	2,946	1,520
Credits/payments made	(110,499)	(75,278)
Ending balance	43,428	30,855
Chargebacks and Discounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	738	516
Current provisions related to sales in current year	7,833	5,617
Adjustments related to prior year sales	(85)	13
Credits/payments made	(7,701)	(5,481)
Ending balance	785	665
Rebates, Fees and other Deductions
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	30,552	22,861
Current provisions related to sales in current year	107,421	73,424
Adjustments related to prior year sales	703	1,507
Credits/payments made	(96,807)	(67,890)
Ending balance	41,869	29,902
Returns
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	253	360
Current provisions related to sales in current year	4,184	1,835
Adjustments related to prior year sales	2,328	0
Credits/payments made	(5,991)	(1,907)
Ending balance	$ 774	$ 288

Valuation allowances and reserves adjustments related to prior period sales.

No definition available.

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

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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

- Definition

Amount of valuation and qualifying accounts and reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09(Column B))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09(Column E))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690

+ Details

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

- Definition

Amount of increase in valuation and qualifying accounts and reserves from charge to cost and expense.

+ References

+ Details

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

- Definition

Amount of decrease in valuation and qualifying accounts and reserves.

+ References

+ Details

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

- Details

Name:	us-gaap_ValuationAllowancesAndReservesTypeAxis=akba_ChargebacksAndDiscountsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationAllowancesAndReservesTypeAxis=akba_RebatesFeesAndOtherDeductionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationAllowancesAndReservesTypeAxis=akba_ReturnsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: