Represents the number of shares for which a tender offer is made to repurchase the shares for cash.

No definition available.

Name:	jmp_TenderOfferToRepurchaseSharesForCashNumberOfShares
Namespace Prefix:	jmp_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the purchase price per share at which a tender offer is made to repurchase the shares for cash.

+ References

No definition available.

+ Details

Name:	jmp_TenderOfferToRepurchaseSharesForCashPurchasePricePerShare
Namespace Prefix:	jmp_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

+ Details

Name:	us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the declared dividend will be paid, in CCYY-MM-DD format.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

+ Details

Name:	us-gaap_DividendPayableDateToBePaidDayMonthAndYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the dividend to be paid was declared, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_DividendsPayableDateDeclaredDayMonthAndYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the holder must own the stock to be entitled to the dividend, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

Name:	us-gaap_DividendsPayableDateOfRecordDayMonthAndYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

Name:	us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The remaining number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

Name:	us-gaap_StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
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Balance Type:
Period Type:

Note 25 - Subsequent Events (Details Textual) - $ / shares	Apr. 29, 2019	May 13, 2019	Mar. 31, 2019	Dec. 13, 2017
Stock Repurchase Program, Number of Shares Authorized to be Repurchased				1,000,000
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased			212,986
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared	$ 0.04
Tender Offer to Repurchase Shares for Cash, Number of Shares		3,000,000
Tender Offer to Repurchase Shares for Cash, Purchase Price Per Share		$ 3.95
Dividends Payable, Date Declared	Apr. 29, 2019
Dividends Payable, Date to be Paid	May 31, 2019
Dividends Payable, Date of Record	May 17, 2019