INVESTMENTS (DETAILS) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 12,428,133	$ 11,987,146
Gross Unrealized Gains (fixed maturities)	231,351	179,218
Gross Unrealized Losses (fixed maturities)	(60,587)	(180,037)
Fair Value (fixed maturities)	12,598,897	11,986,327
Non-credit OTTI in AOCI	(879)	(868)
Cost	614,174	566,219
Gross Unrealized Gains (equities)	133,726	141,951
Gross Unrealized Losses (equities)	(3,140)	(6,183)
Fair Value (equities)	744,760	701,987
US Government and Agency [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	1,607,568	1,421,245
Gross Unrealized Gains (fixed maturities)	4,761	1,405
Gross Unrealized Losses (fixed maturities)	(14,009)	(33,952)
Fair Value (fixed maturities)	1,598,320	1,388,698
Non-credit OTTI in AOCI	0	0
Non-US Government [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	1,238,471	1,208,384
Gross Unrealized Gains (fixed maturities)	30,486	17,990
Gross Unrealized Losses (fixed maturities)	(21,290)	(49,992)
Fair Value (fixed maturities)	1,247,667	1,176,382
Non-credit OTTI in AOCI	0	0
Corporate Debt [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	4,177,454	3,533,585
Gross Unrealized Gains (fixed maturities)	91,862	84,881
Gross Unrealized Losses (fixed maturities)	(5,342)	(10,228)
Fair Value (fixed maturities)	4,263,974	3,608,238
Non-credit OTTI in AOCI	0	0
Agency RMBS [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	2,076,932	2,485,139
Gross Unrealized Gains (fixed maturities)	37,725	21,979
Gross Unrealized Losses (fixed maturities)	(9,078)	(58,291)
Fair Value (fixed maturities)	2,105,579	2,448,827
Non-credit OTTI in AOCI	0	0
CMBS [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	923,294	790,095
Gross Unrealized Gains (fixed maturities)	17,187	11,285
Gross Unrealized Losses (fixed maturities)	(787)	(3,966)
Fair Value (fixed maturities)	939,694	797,414
Non-credit OTTI in AOCI	0	0
Non-Agency RMBS [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	80,243	65,590
Gross Unrealized Gains (fixed maturities)	5,069	2,375
Gross Unrealized Losses (fixed maturities)	(366)	(398)
Fair Value (fixed maturities)	84,946	67,567
Non-credit OTTI in AOCI	(879)	(868)
ABS [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	1,309,555	955,274
Gross Unrealized Gains (fixed maturities)	5,162	6,871
Gross Unrealized Losses (fixed maturities)	(7,792)	(8,694)
Fair Value (fixed maturities)	1,306,925	953,451
Non-credit OTTI in AOCI	0	0
Municipals [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	1,014,616	1,527,834
Gross Unrealized Gains (fixed maturities)	39,099	32,432
Gross Unrealized Losses (fixed maturities)	(1,923)	(14,516)
Fair Value (fixed maturities)	1,051,792	1,545,750
Non-credit OTTI in AOCI	0	0
Common Stock [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost	307,392	345,759
Gross Unrealized Gains (equities)	80,750	98,742
Gross Unrealized Losses (equities)	(3,140)	(6,183)
Fair Value (equities)	385,002	438,318
Exchange-Traded Funds [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost	193,582	106,762
Gross Unrealized Gains (equities)	41,790	32,085
Gross Unrealized Losses (equities)	0	0
Fair Value (equities)	235,372	138,847
Non-U.S. Bond Mutual Funds [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost	113,200	113,698
Gross Unrealized Gains (equities)	11,186	11,124
Gross Unrealized Losses (equities)	0	0
Fair Value (equities)	$ 124,386	$ 124,822