Stockholders' Equity (2020 Shelf Registration Statement) - Additional Information (Detail) $ in Millions	Jul. 23, 2020 USD ($)
2020 Shelf Registration Statement [Member]
Stockholders' Equity [Line Items]
Maximum dollar amount of common stock to be issued under shelf registration statement	$ 200

Maximum dollar amount of common stock to be issued under shelf registration statement.

No definition available.

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Namespace Prefix:	cprx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant