Repurchase of common stock average price per share.

No definition available.

Name:	cprx_RepurchaseOfCommonStockAveragePricePerShare
Namespace Prefix:	cprx_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount authorized for purchase of share under share repurchase plan. Includes, but is not limited to, repurchase of stock and unit of ownership.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 505
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481520/505-30-50-4

+ Details

Name:	srt_StockRepurchaseProgramAuthorizedAmount1
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Expiration date for purchase of share under share repurchase plan, in YYYY-MM-DD format. Includes, but is not limited to, repurchase of stock and unit of ownership.

+ References

+ Details

Name:	srt_StockRepurchaseProgramExpirationDate
Namespace Prefix:	srt_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow to reacquire common stock during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 15
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-15

+ Details

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

- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-SubTopic 10
-Topic 505
-Publisher FASB
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-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Section 50
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
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-Topic 946
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-URI https://asc.fasb.org/1943274/2147479886/946-10-S99-3

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

+ Details

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

- Details

Name:	srt_ShareRepurchaseProgramAxis=cprx_SharePurchaseProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementEquityComponentsAxis=us-gaap_CommonStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
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Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions			1 Months Ended	3 Months Ended		9 Months Ended
	Dec. 31, 2026	Mar. 31, 2021	Nov. 03, 2025	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Oct. 01, 2025
Share Purchase Program [Member]
Subsequent Event [Line Items]
Share repurchase program, expiration date		Mar. 22, 2025
Common Stock [Member]
Subsequent Event [Line Items]
Shares repurchased				0	0	0	0
Common Stock [Member] \| Share Purchase Program [Member]
Subsequent Event [Line Items]
Share repurchase program, authorized		$ 40.0
Shares repurchased				0	0	0	0
Subsequent Event [Member] \| Common Stock [Member] \| Share Purchase Program [Member]
Subsequent Event [Line Items]
Share repurchase program, authorized								$ 200.0
Share repurchase program, expiration date	Dec. 31, 2026
Shares repurchased			405,092
Aggregate purchase price			$ 8.4
Average price per share			$ 20.74