Consideration amount received.

No definition available.

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

- Definition

The maximum amount of payments receivable per drug or program for regulatory milestone payments under the collaboration agreement.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Milestone payments and royalties payable percentage.

+ References

No definition available.

+ Details

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Namespace Prefix:	akca_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Milestone payments and royalties retained percentage.

+ References

No definition available.

+ Details

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Namespace Prefix:	akca_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Payment for sub-license royalty.

+ References

No definition available.

+ Details

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Namespace Prefix:	akca_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Payments on sublicense fee.

+ References

No definition available.

+ Details

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Namespace Prefix:	akca_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Period of time before collaboration partner pays royalties on net sales of product after first commercial sale in Brazil, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Namespace Prefix:	akca_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Proceeds from license agreement.

+ References

No definition available.

+ Details

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Namespace Prefix:	akca_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of separate performance obligations under the collaboration agreement.

+ References

No definition available.

+ Details

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Namespace Prefix:	akca_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The minimum amount of revenue recognized in Latin America by the collaboration partner before paying royalties.

+ References

No definition available.

+ Details

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Namespace Prefix:	akca_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of the sublicense fee paid in common stock.

+ References

No definition available.

+ Details

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Namespace Prefix:	akca_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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

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

- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130531-203044

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130549-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130532-203044

+ Details

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

- Definition

Cash received from licensees for license fees 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=118932676&loc=d3e3536-108585

+ Details

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

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

+ Details

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

- Details

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- Details

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- Details

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- Details

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Data Type:	na
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- Details

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- Details

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Collaboration and License Agreement with PTC Therapeutics - Additional Information (Details)		3 Months Ended		9 Months Ended
	Aug. 01, 2018 USD ($)	Sep. 30, 2019 USD ($) PerformanceObligation	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) PerformanceObligation	Sep. 30, 2018 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue		$ 20,624,000	$ 19,241,000	$ 211,064,000	$ 54,670,000
Cardiometabolic License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Sublicense fee paid	$ 3,000,000
PTC Therapeutics [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment received				12,000,000
Revenue			12,000,000	$ 6,000,000
Deferred revenue			$ 0		$ 0
Number of separate performance obligations \| PerformanceObligation		2		2
Consideration amount received		$ 6,000,000		$ 6,000,000
PTC Therapeutics [Member] \| Akcea [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment received	12,000,000
Payment for sublicense royalty	7,200,000
Payment received	6,000,000
Maximum amount of payments receivable per drug for regulatory milestones	$ 8,000,000
Period before PTC pays royalties on net sales of product after first commercial sale in Brazil	12 months
Minimum revenue recognized in Latin America by PTC before paying royalties	$ 10,000,000
PTC Therapeutics [Member] \| Ionis [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payments on sublicense fee				$ 3,000,000
TEGSEDI [Member] \| PTC Therapeutics [Member] \| Akcea [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments and royalties retained percentage	50.00%
TEGSEDI [Member] \| PTC Therapeutics [Member] \| Ionis [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments and royalties payable percentage	60.00%
WAYLIVRA [Member] \| PTC Therapeutics [Member] \| Ionis [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments and royalties payable percentage	40.00%