INVESTMENTS (DETAILS 5) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net Investment Income [Line Items]
Gross investment income									$ 387,947	$ 427,299	$ 480,178
Investment expenses									(25,517)	(20,407)	(15,700)
Net investment income	102,362	49,396	100,018	110,655	107,889	111,800	82,584	104,619	362,430	406,892	464,478
Fixed Maturities [Member]
Net Investment Income [Line Items]
Gross investment income									337,616	352,357	385,418
Other Investments [Member]
Net Investment Income [Line Items]
Gross investment income									31,856	64,765	82,042
Equities [Member]
Net Investment Income [Line Items]
Gross investment income									11,186	2,900	3,765
Cash And Cash Equivalents [Member]
Net Investment Income [Line Items]
Gross investment income									5,697	5,836	8,302
Short-term Investments [Member]
Net Investment Income [Line Items]
Gross investment income									$ 1,592	$ 1,441	$ 651