RESERVE FOR LOSSES AND LOSS EXPENSES (DETAILS) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Reconciliation of Beginning and Ending Gross Unpaid Losses and Loss Expenses
Gross reserve for losses and loss expenses, beginning of period			$ 9,582,140	$ 9,058,731
Less reinsurance recoverable on unpaid losses, beginning of period			(1,900,112)	(1,825,617)
Net reserve for unpaid losses and loss expenses, beginning of period			7,682,028	7,233,114
Net incurred losses and loss expenses related to:
Current year			1,238,883	1,177,926
Prior years	(85,354)	(42,115)	(128,847)	(96,613)
Net incurred losses and loss expenses			1,110,036	1,081,313
Net paid losses and loss expenses related to:
Current year			(93,218)	(54,732)
Prior years			(857,004)	(732,135)
Net paid losses and loss expenses			(950,222)	(786,867)
Foreign exchange and other			35,122	(130,536)
Net reserve for unpaid losses and loss expenses, end of period	7,876,964	7,397,024	7,876,964	7,397,024
Reinsurance recoverable on unpaid losses, end of period	1,929,024	1,945,793	1,929,024	1,945,793
Gross reserve for losses and loss expenses, end of period	$ 9,805,988	$ 9,342,817	$ 9,805,988	$ 9,342,817