DERIVATIVE INSTRUMENTS (DETAILS) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Asset Derivative Fair Value	$ 2,608	$ 7,264
Liability Derivative Fair Value	16,307	18,329
Other Assets [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Asset Derivative Fair Value	2,608	7,264
Other Liabilities [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Liability Derivative Fair Value	16,307	18,329
Investment Portfolio [Member] \| Foreign Exchange Forward Contracts [Member] \| Not Designated as Hedging Instruments [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Derivative Notional Amount	218,921	161,678
Investment Portfolio [Member] \| Foreign Exchange Forward Contracts [Member] \| Other Assets [Member] \| Not Designated as Hedging Instruments [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Asset Derivative Fair Value	1,422	3,925
Investment Portfolio [Member] \| Foreign Exchange Forward Contracts [Member] \| Other Liabilities [Member] \| Not Designated as Hedging Instruments [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Liability Derivative Fair Value	22	12
Investment Portfolio [Member] \| Interest Rate Swap [Member] \| Not Designated as Hedging Instruments [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Derivative Notional Amount	0	140,000
Investment Portfolio [Member] \| Interest Rate Swap [Member] \| Other Assets [Member] \| Not Designated as Hedging Instruments [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Asset Derivative Fair Value	0	0
Investment Portfolio [Member] \| Interest Rate Swap [Member] \| Other Liabilities [Member] \| Not Designated as Hedging Instruments [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Liability Derivative Fair Value	0	248
Underwriting Portfolio [Member] \| Foreign Exchange Forward Contracts [Member] \| Not Designated as Hedging Instruments [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Derivative Notional Amount	712,136	577,836
Underwriting Portfolio [Member] \| Foreign Exchange Forward Contracts [Member] \| Other Assets [Member] \| Not Designated as Hedging Instruments [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Asset Derivative Fair Value	0	3,228
Underwriting Portfolio [Member] \| Foreign Exchange Forward Contracts [Member] \| Other Liabilities [Member] \| Not Designated as Hedging Instruments [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Liability Derivative Fair Value	9,323	2,781
Underwriting Portfolio [Member] \| Weather Related Derivative [Member] \| Not Designated as Hedging Instruments [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Derivative Notional Amount	53,206	58,124
Underwriting Portfolio [Member] \| Weather Related Derivative [Member] \| Other Assets [Member] \| Not Designated as Hedging Instruments [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Asset Derivative Fair Value	35	111
Underwriting Portfolio [Member] \| Weather Related Derivative [Member] \| Other Liabilities [Member] \| Not Designated as Hedging Instruments [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Liability Derivative Fair Value	6,962	15,288
Underwriting Portfolio [Member] \| Commodity Contract [Member] \| Not Designated as Hedging Instruments [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Derivative Notional Amount	77,875	0
Underwriting Portfolio [Member] \| Commodity Contract [Member] \| Other Assets [Member] \| Not Designated as Hedging Instruments [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Asset Derivative Fair Value	1,151	0
Underwriting Portfolio [Member] \| Commodity Contract [Member] \| Other Liabilities [Member] \| Not Designated as Hedging Instruments [Member]
Derivative Fair Values on Consolidated Balance Sheet [Line Items]
Liability Derivative Fair Value	$ 0	$ 0

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

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