VARIABLE INTEREST ENTITIES (Schedule of Variable Interest Entities) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
VARIABLE INTEREST ENTITIES [Abstract]
Assets recorded related to VIEs	$ 381,826	$ 228,233
Unfunded loan commitments to VIEs	307,609	310,750
Maximum exposure to loss	$ 689,435	$ 538,983

Unfunded loan commitment supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

No definition available.

+ Details

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Namespace Prefix:	jcap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Difference between the carrying amount of assets and liabilities in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the variable interest entity (VIE) and the reporting entity's maximum exposure to loss as a result of its involvement with the VIE, where the reporting entity is not the VIE's primary beneficiary.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=77990344&loc=d3e5728-111685

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount of the assets in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph a
-URI http://asc.fasb.org/extlink&oid=77990344&loc=d3e5728-111685

+ Details

Name:	us-gaap_VariableInterestEntityNonconsolidatedCarryingAmountAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
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