RESERVE FOR LOSSES AND LOSS EXPENSES - Narrative (Details)	12 Months Ended
Dec. 31, 2018
Minimum
Claims Development [Line Items]
Development for an accident year or underwriting year, recognition period	1 year
Maximum
Claims Development [Line Items]
Development for an accident year or underwriting year, recognition period	3 years

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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