INVESTMENTS (Tables)

12 Months Ended

Dec. 31, 2011

Available For Sale Securities And Held To Maturity Securities [Table Text Block]

			Included in Accumulated Other Comprehensive Income (“AOCI”)
					Gross Unrealized Losses
December 31, 2011 (U.S. dollars in thousands)	Cost or Amortized Cost		Gross Unrealized Gains		Related to Changes In Estimated Fair Value			OTTI Included In Other Comprehensive Income (Loss)(1)			Fair Value
Fixed maturities – AFS
U.S. Government and Government- Related/Supported (2)	$	1,864,354	$	130,874	$	(4,245	)	$	—		$	1,990,983
Corporate (3) (4)		10,212,083		539,389		(237,291	)		(51,666	)		10,462,515
Residential mortgage-backed securities – Agency		5,189,473		193,782		(3,849	)		—			5,379,406
Residential mortgage-backed securities – Non-Agency		851,557		19,667		(112,867	)		(116,542	)		641,815
Commercial mortgage-backed securities		927,684		56,704		(2,405	)		(7,148	)		974,835
Collateralized debt obligations		843,553		6,624		(186,578	)		(4,997	)		658,602
Other asset-backed securities		995,903		18,534		(21,776	)		(6,305	)		986,356
U.S. States and political subdivisions of the States		1,698,573		101,025		(2,220	)		—			1,797,378
Non-U.S. Sovereign Government, Supranational and Government-Related/Supported (2)		3,188,535		127,439		(17,839	)		—			3,298,135
Total fixed maturities – AFS	$	25,771,715	$	1,194,038	$	(589,070	)	$	(186,658	)	$	26,190,025
Total short-term investments (2) (3)	$	359,378	$	519	$	(834	)	$	—		$	359,063
Total equity securities	$	480,685	$	27,947	$	(40,435	)	$	—		$	468,197
Total investments – AFS	$	26,611,778	$	1,222,504	$	(630,339	)	$	(186,658	)	$	27,017,285
Fixed maturities – HTM
U.S. Government and Government- Related/Supported (2)	$	10,399	$	1,510	$	—		$	—		$	11,909
Corporate		1,298,266		91,313		(14,747	)		—			1,374,832
Residential mortgage-backed securities – Non-Agency		80,955		6,520		(32	)		—			87,443
Other asset-backed securities		280,684		20,875		(6	)		—			301,553
Non-U.S. Sovereign Government, Supranational and Government-Related/Supported (2)		998,674		127,227		(5,950	)		—			1,119,951
Total fixed maturities – HTM	$	2,668,978	$	247,445	$	(20,735	)	$	—		$	2,895,688

			Included in Accumulated Other Comprehensive Income (“AOCI”)
					Gross Unrealized Losses
December 31, 2010 (U.S. dollars in thousands)	Cost or Amortized Cost		Gross Unrealized Gains		Related to Changes In Estimated Fair Value			OTTI Included In Other Comprehensive Income (Loss)(1)			Fair Value
Fixed maturities – AFS
U.S. Government and Government-Related/Supported (2)	$	2,499,079	$	102,685	$	(36,320	)	$	—		$	2,565,444
Corporate (3) (4)		10,962,804		361,154		(281,849	)		(73,138	)		10,968,971
Residential mortgage-backed securities – Agency		5,059,249		153,106		(8,644	)		—			5,203,711
Residential mortgage-backed securities – Non-Agency		1,257,474		26,361		(133,761	)		(128,251	)		1,021,823
Commercial mortgage-backed securities		1,135,075		55,852		(7,960	)		(10,460	)		1,172,507
Collateralized debt obligations		920,501		11,014		(188,563	)		(8,814	)		734,138
Other asset-backed securities		979,539		16,111		(26,954	)		(8,164	)		960,532
U.S. States and political subdivisions of the States		1,379,150		16,755		(35,449	)		—			1,360,456
Non-U.S. Sovereign Government, Supranational and Government-Related/Supported (2)		3,129,971		70,499		(45,947	)		—			3,154,523
Total fixed maturities – AFS	$	27,322,842	$	813,537	$	(765,447	)	$	(228,827	)	$	27,142,105
Total short-term investments (2) (3)	$	450,491	$	680	$	(490	)	$	—		$	450,681
Total equity securities	$	56,737	$	28,083	$	(53	)	$	—		$	84,767
Total investments – AFS	$	27,830,070	$	842,300	$	(765,990	)	$	(228,827	)	$	27,677,553
Fixed maturities – HTM
U.S. Government and Government- Related/Supported (2)	$	10,541	$	164	$	(9	)	$	—		$	10,696
Corporate		1,337,797		6,370		(16,325	)		—			1,327,842
Residential mortgage-backed securities – Non-Agency		82,763		634		(546	)		—			82,851
Other asset-backed securities		287,109		1,134		(1,410	)		—			286,833
Non-U.S. Sovereign Government, Supranational and Government-Related/Supported (2)		1,010,125		30,680		(6,401	)		—			1,034,404
Total fixed maturities – HTM	$	2,728,335	$	38,982	$	(24,691	)	$	—		$	2,742,626

Contractual MaturitiesOf Available For Sale Securities And Held To Maturity Income Securities [Table Text Block]

	2011 (1)				2010 (1)
(U.S. dollars in thousands)	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Fixed maturities - AFS
Due less than one year	$	2,025,446	$	2,041,814	$	1,583,265	$	1,570,909
Due after 1 through 5 years		7,874,145		8,049,150		9,021,926		9,118,229
Due after 5 through 10 years		3,788,673		3,953,496		4,137,260		4,198,362
Due after 10 years		3,275,281		3,504,551		3,228,553		3,161,894
		16,963,545		17,549,011		17,971,004		18,049,394
Residential mortgage-backed securities – Agency		5,189,473		5,379,406		5,059,249		5,203,711
Residential mortgage-backed securities – Non-Agency		851,557		641,815		1,257,474		1,021,823
Commercial mortgage-backed securities		927,684		974,835		1,135,075		1,172,507
Collateralized debt obligations		843,553		658,602		920,501		734,138
Other asset-backed securities		995,903		986,356		979,539		960,532
Total mortgage and asset-backed securities		8,808,170		8,641,014		9,351,838		9,092,711
Total fixed maturities - AFS	$	25,771,715	$	26,190,025	$	27,322,842	$	27,142,105
Fixed maturities - HTM
Due less than one year	$	11,796	$	11,768	$	—	$	—
Due after 1 through 5 years		122,091		123,871		125,449		125,416
Due after 5 through 10 years		393,865		402,424		348,797		346,494
Due after 10 years		1,779,587		1,968,629		1,884,217		1,901,032
		2,307,339		2,506,692		2,358,463		2,372,942
Residential mortgage-backed securities – Non-Agency		80,955		87,443		82,763		82,851
Other asset-backed securities		280,684		301,553		287,109		286,833
Total mortgage and asset-backed securities		361,639		388,996		369,872		369,684
Total fixed maturities - HTM	$	2,668,978	$	2,895,688	$	2,728,335	$	2,742,626

Available For Sale Securities Continuous Unrealised Loss Position [Text Block]

	Less than 12 months					Equal to or greater than 12 months
December 31, 2011 (U.S. dollars in thousands)	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses (1)
Fixed maturities and short-term investments - AFS:
U.S. Government and Government-Related/Supported	$	289,260	$	(332	)	$	43,622	$	(3,984	)
Corporate (2) (3)		1,108,177		(42,978	)		1,200,717		(246,566	)
Residential mortgage-backed securities – Agency		310,318		(849	)		36,960		(3,000	)
Residential mortgage-backed securities – Non-Agency		106,294		(31,714	)		449,138		(197,695	)
Commercial mortgage-backed securities		69,109		(2,716	)		39,444		(6,837	)
Collateralized debt obligations		3,357		(2,261	)		636,362		(189,456	)
Other asset-backed securities		197,585		(2,497	)		146,130		(25,584	)
U.S. States and political subdivisions of the States		25,309		(199	)		27,646		(2,021	)
Non-U.S. Sovereign Government, Supranational and Government-Related		265,766		(4,707	)		202,890		(13,166	)
Total fixed maturities and short-term investments - AFS	$	2,375,175	$	(88,253	)	$	2,782,909	$	(688,309	)
Total equity securities (4)	$	361,585	$	(40,435	)	$	—	$	—
Fixed maturities – HTM:
U.S. Government and Government-Related/Supported	$	—	$	—		$	—	$	—
Corporate		155,579		(8,084	)		62,343		(6,663	)
Residential mortgage-backed securities – Non-Agency		9,372		(32	)		—		—
Other asset-backed securities		—		—			1,106		(6	)
Non-U.S. Sovereign Government, Supranational and Government-Related/Supported		79,242		(1,206	)		18,330		(4,744	)
Total fixed maturities – HTM	$	244,193	$	(9,322	)	$	81,779	$	(11,413	)

	Less than 12 months					Equal to or greater than 12 months
December 31, 2010 (U.S. dollars in thousands)	Fair Value		Gross Unrealized Losses (1)			Fair Value		Gross Unrealized Losses (1)
Fixed maturities and short-term investments - AFS:
U.S. Government and Government-Related/Supported	$	307,082	$	(25,482	)	$	117,394	$	(10,417	)
Corporate (2) (3)		2,271,887		(80,276	)		1,627,083		(275,023	)
Residential mortgage-backed securities – Agency		280,390		(6,736	)		34,186		(1,913	)
Residential mortgage-backed securities – Non-Agency		40,052		(2,574	)		843,168		(259,715	)
Commercial mortgage-backed securities		46,419		(2,472	)		69,475		(15,967	)
Collateralized debt obligations		2,500		(51	)		715,295		(197,535	)
Other asset-backed securities		122,548		(1,619	)		226,946		(33,546	)
U.S. States and political subdivisions of the States		734,893		(30,033	)		40,907		(5,452	)
Non-U.S. Sovereign Government, Supranational and Government-Related		459,686		(5,116	)		418,322		(40,837	)
Total fixed maturities and short-term investments - AFS	$	4,265,457	$	(154,359	)	$	4,092,776	$	(840,405	)
Total equity securities	$	158	$	(53	)	$	—	$	—
Fixed maturities – HTM:
U.S. Government and Government-Related/Supported	$	1,755	$	(9	)	$	—	$	—
Corporate		764,397		(16,325	)		—		—
Residential mortgage-backed securities – Non-Agency		37,899		(546	)		—		—
Other asset-backed securities		232,673		(1,410	)		—		—
Non-U.S. Sovereign Government, Supranational and Government-Related/Supported		175,382		(6,401	)		—		—
Total fixed maturities – HTM	$	1,212,106	$	(24,691	)	$	—	$	—

Investment Income [Table Text Block]

Year ended December 31
(U.S. dollars in thousands)	2011			2010			2009
Fixed maturities, short-term investments and cash equivalents	$	1,178,038		$	1,245,185		$	1,369,503
Equity securities and other investments		17,804			20,693			13,753
Funds withheld		12,240			12,738			14,649
Total gross investment income		1,208,082			1,278,616			1,397,905
Investment expenses		(70,313	)		(80,578	)		(78,082	)
Net investment income	$	1,137,769		$	1,198,038		$	1,319,823

Gain (Loss) on Investments [Table Text Block]

Year ended December 31
(U.S. dollars in thousands)	2011			2010			2009
Net realized gains (losses):
Fixed maturities, short-term investments, cash and cash equivalents:
Gross realized gains	$	185,530		$	133,521		$	349,629
Gross realized losses on investments sold		(225,360	)		(193,396	)		(405,342	)
OTTI on investments, net of amounts transferred to other comprehensive income		(159,435	)		(197,377	)		(811,572	)
Net realized (losses)		(199,265	)		(257,252	)		(867,285	)
Equity securities:
Gross realized gains		2,194			11,605			65,289
Gross realized losses on investments sold		(4,264	)		(11,195	)		(129,516	)
OTTI on investments, net of amounts transferred to other comprehensive income		—			—			—
Net realized gains (losses)		(2,070	)		410			(64,227	)
Other investments:
Gross realized gains		18,505			4,889			27,647
Gross realized losses on investments sold		(4,792	)		(11,094	)		(5,763	)
OTTI on investments, net of amounts transferred to other comprehensive income		(737	)		(7,756	)		(886	)
Net realized gains (losses)		12,976			(13,961	)		20,998
Realized loss on sale of U.S. life reinsurance business		—			—			(10,923	)
Net realized (losses) on investments		(188,359	)		(270,803	)		(921,437	)
Net realized and unrealized (losses) on investment related derivative instruments		(22,981	)		(16,321	)		(29,709	)
Net realized (losses) on investments and net realized and unrealized (losses) on investment related derivative instruments		(211,340	)		(287,124	)		(951,146	)
Change in unrealized gains (losses):
Fixed maturities and short-term investments, available for sale		598,542			1,095,762			2,112,244
Fixed maturities, held to maturity		212,419			30,039			(15,748	)
Equity securities		(40,518	)		22,595			(18,619	)
Affiliates and other investments		25,268			44,314			14,464
Net change in unrealized gains (losses) on investments		795,711			1,192,710			2,092,341
Total net realized (losses) on investments, net realized and unrealized (losses) on investment related derivative instruments, and net change in unrealized gains (losses) on investments	$	584,371		$	905,586		$	1,141,195

Other than Temporary Impairment, Credit Losses Recognized in Earnings [Table Text Block]

	OTTI related to credit losses recognized in earnings
Year Ended December 31,
(U.S. dollars in thousands)	2011			2010
Balance, January 1	$	426,372		$	537,121
Credit loss impairment recognized in the current period on securities not previously impaired		28,910			55,515
Credit loss impairments previously recognized on securities which matured, paid down, prepaid or were sold during the period		(209,187	)		(125,653	)
Credit loss impairments previously recognized on securities impaired to fair value during the period		—			(130,891	)
Additional credit loss impairments recognized in the current period on securities previously impaired		88,016			113,292
Accretion of credit loss impairments previously recognized due to an increase in cash flows expected to be collected		(732	)		(23,012	)
Balance, December 31	$	333,379		$	426,372