INVESTMENTS (DETAILS 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule Of Available For Sale Securities [Line Items]
Due in one year or less (amortized cost)	$ 508,448	$ 424,077
Due after one year through five years (amortized cost)	4,387,194	4,925,780
Due after five years through ten years (amortized cost)	2,042,045	1,755,248
Due after ten years (amortized cost)	235,343	207,407
Total fixed maturities with a single maturity date (amortized cost)	7,173,030	7,312,512
Total (amortized cost)	12,012,633	12,185,973
Due in one year or less (fair value)	503,179	423,265
Due after one year through five years (fair value)	4,349,800	4,892,411
Due after five years through ten years (fair value)	2,016,713	1,695,641
Due after ten years (fair value)	237,806	208,288
Total fixed maturities with a single maturity date (fair value)	7,107,498	7,219,605
Fair Value (fixed maturities)	12,012,894	12,129,273
Due in one year or less (% of total fair value)	4.20%	3.50%
Due after one year through five years (% of total fair value)	36.20%	40.30%
Due after five years through ten years (% of total fair value)	16.80%	14.00%
Due after ten years (% of total fair value)	2.00%	1.70%
Fixed maturities with a single maturity date (% of total fair value)	59.20%	59.50%
Total	100.00%	100.00%
Agency RMBS [Member]
Schedule Of Available For Sale Securities [Line Items]
Fixed maturities without a single maturity date (amortized cost)	2,150,598	2,241,581
Total (amortized cost)	2,150,598	2,241,581
Fixed maturities without a single maturity date (fair value)	2,200,243	2,278,108
Fair Value (fixed maturities)	2,200,243	2,278,108
Fixed maturities without a single maturity date (% of total fair value)	18.30%	18.80%
CMBS [Member]
Schedule Of Available For Sale Securities [Line Items]
Fixed maturities without a single maturity date (amortized cost)	1,111,327	1,085,618
Total (amortized cost)	1,111,327	1,085,618
Fixed maturities without a single maturity date (fair value)	1,131,323	1,096,888
Fair Value (fixed maturities)	1,131,323	1,096,888
Fixed maturities without a single maturity date (% of total fair value)	9.40%	9.00%
Non-Agency RMBS [Member]
Schedule Of Available For Sale Securities [Line Items]
Fixed maturities without a single maturity date (amortized cost)	77,185	71,236
Total (amortized cost)	77,185	71,236
Fixed maturities without a single maturity date (fair value)	78,001	73,086
Fair Value (fixed maturities)	78,001	73,086
Fixed maturities without a single maturity date (% of total fair value)	0.60%	0.60%
ABS [Member]
Schedule Of Available For Sale Securities [Line Items]
Fixed maturities without a single maturity date (amortized cost)	1,500,493	1,475,026
Total (amortized cost)	1,500,493	1,475,026
Fixed maturities without a single maturity date (fair value)	1,495,829	1,461,586
Fair Value (fixed maturities)	$ 1,495,829	$ 1,461,586
Fixed maturities without a single maturity date (% of total fair value)	12.50%	12.10%

Amount of available-for-sale debt securities at fair value maturing in the next rolling twelve months following the latest balance sheet presented, expressed as a percentage of the total fair value of debt securities classified as available-for-sale.

No definition available.