Minimum liquidity covenant amount.

No definition available.

Name:	kpti_MinimumLiquidityCovenantAmount
Namespace Prefix:	kpti_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the frequency of the required periodic payments of interest, principal, or both, and the amount, if set, or a description of a formula upon which payment is based.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480657/210-10-S50-8

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

+ Details

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 830
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481674/830-30-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 855
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483399/855-10-50-2

+ Details

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Balance Type:	na
Period Type:	duration

- Details

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- Details

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

- Details

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

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
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Period Type:

Subsequent Event - Senior Secured Term Loan - Additional Information (Detail) - USD ($) $ in Millions		1 Months Ended	6 Months Ended	12 Months Ended
	Oct. 11, 2026	Oct. 31, 2025	Jun. 30, 2026	Oct. 10, 2026
Scenario, Forecast [Member]
Subsequent Event [Line Items]
Minimum liquidity covenant amount	$ 25.0			$ 25.0
Line of Credit [Member] \| Secured Overnight Financing Rate [Member]
Subsequent Event [Line Items]
Rate margin		10.25%	9.25%
Line of Credit [Member] \| Base Rate [Member]
Subsequent Event [Line Items]
Rate margin		3.00%	3.00%
Amended Term Loan [Member]
Subsequent Event [Line Items]
Interest, payment terms		Interest incurred on borrowings under the Amended Term Loan from July 1, 2025 to June 30, 2026 was payable in-kind. Interest incurred on borrowings under the Amended Term Loan after June 30, 2026 is payable in cash quarterly in arrears on March 31, June 30, September 30, and December 31 of each year