Stockholders' Equity (2016 Shelf Registration Statement) - Additional Information (Detail)	Dec. 23, 2016 USD ($)
2016 Shelf Registration Statement [Member]
Stockholders' Equity [Line Items]
Maximum dollar amount of common stock to be issued under shelf registration statement	$ 33,800,000

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