INVESTMENTS - (Net Realized Gains (Losses) by Major Investment Category (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Total gross realized gains	$ 11,758	$ 7,472	$ 6,231
Total gross realized losses	(3,210)	(4,427)	(2,615)
Net realized gains on investments	8,548	3,045	3,616
Debt Securities [Member]
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Total gross realized gains	1,814	3,208	1,272
Total gross realized losses	(1,671)	(1,614)	(805)
Equity Securities [Member]
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Total gross realized gains	9,944	4,264	4,959
Total gross realized losses	$ (1,539)	$ (2,813)	$ (1,810)

This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27357-111563

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