Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2011

Fair Value, by Balance Sheet Grouping [Table Text Block]

June 30, 2011 (U.S. dollars in thousands) (Unaudited)	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Collateral and Counterparty Netting			Balance at June 30, 2011
Assets
U.S. Government and Government-Related/Supported	$	—	$	1,518,812	$	—	$	—		$	1,518,812
Corporate (1)		—		10,264,823		4,768		—			10,269,591
Residential mortgage-backed securities – Agency		—		5,660,955		15,385		—			5,676,340
Residential mortgage-backed securities – Non-Agency		—		770,092		3,194		—			773,286
Commercial mortgage-backed securities		—		1,141,839		4,563		—			1,146,402
Collateralized debt obligations		—		8,718		727,239		—			735,957
Other asset-backed securities		—		977,460		6,313		—			983,773
U.S. States and political subdivisions of the States		—		1,463,803		—		—			1,463,803
Non-U.S. Sovereign Government, Supranational and Government-Related		—		2,583,722		—		—			2,583,722
Total fixed maturities, at fair value	$	—	$	24,390,224	$	761,462	$	—		$	25,151,686
Equity securities, at fair value		244,798		73,897		—		—			318,695
Short-term investments, at fair value (1)(2)		—		2,841,070		10,753		—			2,851,823
Total investments available for sale	$	244,798	$	27,305,191	$	772,215	$	—		$	28,322,204
Cash equivalents (3)		1,030,924		611,616		—		—			1,642,540
Other investments (4)		—		527,730		114,540		—			642,270
Other assets (5)(6)		—		109,270		409		(36,942	)		72,737
Total assets accounted for at fair value	$	1,275,722	$	28,553,807	$	887,164	$	(36,942	)	$	30,679,751
Liabilities
Financial instruments sold, but not yet purchased (7)	$	—	$	26,149	$	—	$	—		$	26,149
Other liabilities (5)(6)		—		39,802		50,054		(4,011	)		85,845
Total liabilities accounted for at fair value	$	—	$	65,951	$	50,054	$	(4,011	)	$	111,994

December 31, 2010 (U.S. dollars in thousands)	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Collateral and Counterparty Netting			Balance at December 31, 2010
Assets
U.S. Government and Government-Related/Supported	$	—	$	2,127,491	$	—	$	—		$	2,127,491
Corporate (1)		—		10,325,725		35,158		—			10,360,883
Residential mortgage-backed securities – Agency		—		5,134,491		30,255		—			5,164,746
Residential mortgage-backed securities – Non- Agency		—		1,016,124		4,964		—			1,021,088
Commercial mortgage-backed securities		—		1,170,884		1,623		—			1,172,507
Collateralized debt obligations		—		12,566		721,097		—			733,663
Other asset-backed securities		—		924,181		24,650		—			948,831
U.S. States and political subdivisions of the States		—		1,351,677		—		—			1,351,677
Non-U.S. Sovereign Government, Supranational and Government-Related		—		2,659,626		3,667		—			2,663,293
Total fixed maturities, at fair value	$	—	$	24,722,765	$	821,414	$	—		$	25,544,179
Equity securities, at fair value		71,284		13,483		—		—			84,767
Short-term investments, at fair value (1)(2)		—		2,046,424		2,183		—			2,048,607
Total investments available for sale	$	71,284	$	26,782,672	$	823,597	$	—		$	27,677,553
Cash equivalents (3)		1,358,619		540,646		—		—			1,899,265
Other investments (4)		—		490,320		133,717		—			624,037
Other assets (5)(6)		—		108,056		7,882		(22,995	)		92,943
Total assets accounted for at fair value	$	1,429,903	$	27,921,694	$	965,196	$	(22,995	)	$	30,293,798
Liabilities
Financial instruments sold, but not yet purchased (7)	$	256	$	21,270	$	—	$	—		$	21,526
Other liabilities (5)(6)		—		13,591		47,077		—			60,668
Total liabilities accounted for at fair value	$	256	$	34,861	$	47,077	$	—		$	82,194

Fair Value, Assets And Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Text Block]

	Level 3 Assets and Liabilities Three Months Ended June 30, 2011
(U.S. dollars in thousands) (Unaudited)	Corporate			Residential mortgage-backed securities – Agency			Residential mortgage-backed securities – Non Agency			Commercial mortgage-backed securities			Collateralized debt obligations
Balance, beginning of period	$	34,866		$	32,987		$	3,335		$	1,757		$	742,284
Realized gains (losses)		(247	)		—			—			207			(419	)
Movement in unrealized gains (losses)		354			61			(22	)		(527	)		9,644
Purchases and issuances		—			—			—			3,155			2,379
Sales and settlements		(7,567	)		(165	)		(119	)		(29	)		(29,274	)
Transfers into Level 3		—			11,276			—			—			2,625
Transfers out of Level 3		(22,638	)		(28,774	)		—			—			—
Fixed maturities to short-term investments classification change		—			—			—			—			—
Balance, end of period	$	4,768		$	15,385		$	3,194		$	4,563		$	727,239
Movement in total gains (losses) above relating to instruments still held at the reporting date	$	71		$	61		$	(22	)	$	(320	)	$	8,419

	Level 3 Assets and Liabilities Three Months Ended June 30, 2011 (Continued)
(U.S. dollars in thousands) (Unaudited)	Other asset backed securities			Non-U.S. Sovereign Government and Supranationals and Government Related		Short-term Investments			Other investments			Derivative Contracts - Net
Balance, beginning of period	$	12,371		$	—	$	286		$	144,834		$	(36,810	)
Realized gains (losses)		161			—		—			12,155			—
Movement in unrealized gains (losses)		100			—		4,576			(1,982	)		(12,725	)
Purchases and issuances		—			—		—			6,254			—
Sales and settlements		(207	)		—		(221	)		(46,421	)		(110	)
Transfers into Level 3		—			—		—			—			—
Transfers out of Level 3		—			—		—			(300	)		—
Fixed maturities to short-term investments classification change		(6,112	)		—		6,112			—			—
Balance, end of period	$	6,313		$	—	$	10,753		$	114,540		$	(49,645	)
Movement in total gains (losses) above relating to instruments still held at the reporting date	$	290		$	—	$	4,588		$	9,285		$	(12,725	)

	Level 3 Assets and Liabilities Six Months Ended June 30, 2011
(U.S. dollars in thousands) (Unaudited)	Corporate			Residential mortgage-backed securities – Agency			Residential mortgage-backed securities – Non Agency			Commercial mortgage-backed securities			Collateralized debt obligations
Balance, beginning of period	$	35,158		$	30,255		$	4,964		$	1,623		$	721,097
Realized gains (losses)		(279	)		—			—			(678	)		(1,071	)
Movement in unrealized gains (losses)		205			(50	)		(16	)		514			36,471
Purchases and issuances		6,877			—			—			3,155			2,379
Sales and settlements		(8,369	)		(286	)		(374	)		(51	)		(33,523	)
Transfers into Level 3		—			—			—			—			1,886
Transfers out of Level 3		(28,824	)		(14,534	)		(1,380	)		—			—
Fixed maturities to short-term investments classification change		—			—			—			—			—
Balance, end of period	$	4,768		$	15,385		$	3,194		$	4,563		$	727,239
Movement in total gains (losses) above relating to instruments still held at the reporting date	$	6		$	(50	)	$	(16	)	$	(152	)	$	33,777

	Level 3 Assets and Liabilities Six Months Ended June 30, 2011 (Continued)
(U.S. dollars in thousands) (Unaudited)	Other asset backed securities			Non-U.S. Sovereign Government and Supranationals and Government Related			Short-term Investments			Other investments			Derivative Contracts - Net
Balance, beginning of period	$	24,650		$	3,667		$	2,183		$	133,717		$	(39,195	)
Realized gains (losses)		(317	)		—			—			12,155			—
Movement in unrealized gains (losses)		1,698			—			5,098			7,492			(10,276	)
Purchases and issuances		—			—			—			8,115			—
Sales and settlements		(9,857	)		—			(1,358	)		(46,939	)		(174	)
Transfers into Level 3		—			—			—			—			—
Transfers out of Level 3		(5,031	)		(3,667	)		—			—			—
Fixed maturities to short-term investments classification change		(4,830	)		—			4,830			—			—
Balance, end of period	$	6,313		$	—		$	10,753		$	114,540		$	(49,645	)
Movement in total gains (losses) above relating to instruments still held at the reporting date	$	1,031		$	—		$	5,162		$	17,337		$	(10,276	)

	Level 3 Assets and Liabilities Three Months Ended June 30, 2010
(U.S. dollars in thousands) (Unaudited)	Corporate			Residential mortgage-backed securities – Agency		Residential mortgage-backed securities – Non Agency			Commercial mortgage-backed securities			Collateralized debt obligations
Balance, beginning of period	$	9,493		$	—	$	30,000		$	41,655		$	711,749
Realized gains (losses)		117			—		(2,681	)		(286	)		(7,930	)
Movement in unrealized gains (losses)		33			—		474			(60	)		(13,889	)
Purchases and issuances		22,944			1,226		—			—			—
Sales and settlements		(257)			—		(1,748	)		—			(467	)
Transfers into Level 3		12,146			—		7,201			—			—
Transfers out of Level 3		(4,800	)		—		(23,238	)		(40,882	)		(1,280	)
Fixed maturities to short-term investments classification change		—			—		—			—			(1,416	)
Balance, end of period	$	39,676		$	1,226	$	10,008		$	427		$	686,767
Movement in total gains (losses) above relating to instruments still held at the reporting date	$	316		$	—	$	340		$	(54	)	$	(15,385	)

	Level 3 Assets and Liabilities Three Months Ended June 30, 2010 (Continued)
(U.S. dollars in thousands) (Unaudited)	Other asset backed securities			Non-U.S. Sovereign Government and Supranationals and Government Related			Short-term Investments			Other investments			Derivative Contracts - Net
Balance, beginning of period	$	52,082		$	3,242		$	6,566		$	83,088		$	104,474
Realized gains (losses)		(7,742	)		—			(1,146	)		2,565			—
Movement in unrealized gains (losses)		5,490			(60	)		(160	)		1,567			53,027
Purchases and issuances		—			—			—			6,162			5,522
Sales and settlements		(75	)		—			(717	)		(525	)		(112	)
Transfers into Level 3		—			—			—			—			—
Transfers out of Level 3		(27,234	)		—			(878	)		—			—
Fixed maturities to short-term investments classification change		—			—			1,416			—			—
Balance, end of period	$	22,521		$	3,182		$	5,081		$	92,857		$	162,911
Movement in total gains (losses) above relating to instruments still held at the reporting date	$	(3,221	)	$	(60	)	$	(58	)	$	1,567		$	53,027

	Level 3 Assets and Liabilities Six Months Ended June 30, 2010
(U.S. dollars in thousands) (Unaudited)	Corporate			Residential mortgage-backed securities – Agency			Residential mortgage-backed securities – Non Agency			Commercial mortgage-backed securities			Collateralized debt obligations
Balance, beginning of period	$	10,311		$	7,894		$	42,190		$	2,755		$	190,663
Realized gains (losses)		(4,438	)		—			(5,674	)		(209	)		(13,174	)
Movement in unrealized gains (losses)		480			—			706			16			16,636
Purchases and issuances		23,275			1,226			9			—			—
Sales and settlements		(1,135	)		—			(853	)		(706	)		(14	)
Transfers into Level 3		14,951			—			8,433			—			495,734
Transfers out of Level 3		(3,768	)		(7,894	)		(34,803	)		(1,429	)		(1,356	)
Fixed maturities to short-term investments classification change		—			—			—			—			(1,722	)
Balance, end of period	$	39,676		$	1,226		$	10,008		$	427		$	686,767
Movement in total gains (losses) above relating to instruments still held at the reporting date	$	599		$	—		$	405		$	(151	)	$	15,574

	Level 3 Assets and Liabilities Six Months Ended June 30, 2010 (Continued)
(U.S. dollars in thousands) (Unaudited)	Other asset backed securities			Non-U.S. Sovereign Government and Supranationals and Government Related			Short-term Investments			Other investments			Derivative Contracts - Net
Balance, beginning of period	$	38,179		$	3,217		$	6,486		$	75,584		$	100,515
Realized gains (losses)		(14,082	)		—			(4,502	)		2,565			—
Movement in unrealized gains (losses)		9,236			(102	)		2,512			5,552			51,637
Purchases and issuances		4,513			—			—			10,908			10,985
Sales and settlements		(76	)		—			(2,124	)		(1,752	)		(226	)
Transfers into Level 3		204			67			987			—			—
Transfers out of Level 3		(15,453	)		—			—			—			—
Fixed maturities to short-term investments classification change		—			—			1,722			—			—
Balance, end of period	$	22,521		$	3,182		$	5,081		$	92,857		$	162,911
Movement in total gains (losses) above relating to instruments still held at the reporting date	$	(1,168	)	$	(102	)	$	2,193		$	5,552		$	51,637

Schedule Of Financial Instruments Not Carried at Fair Value [Text Block]

	(Unaudited) June 30, 2011				December 31, 2010
(U.S. dollars in thousands)	Carrying Value		Fair Value		Carrying Value		Fair Value
Fixed maturities, held to maturity	$	2,843,371	$	2,819,505	$	2,728,335	$	2,742,626
Other investments – structured transactions	$	325,880	$	323,750	$	327,686	$	317,524
Financial Assets	$	3,169,251	$	3,143,255	$	3,056,021	$	3,060,150
Deposit liabilities	$	1,666,275	$	1,730,727	$	1,684,606	$	1,737,107
Notes payable and debt		2,461,426		2,628,570		2,464,410		2,627,897
Financial Liabilities	$	4,127,701	$	4,359,297	$	4,149,016	$	4,365,004
Non-controlling interest - Redeemable Series C preference ordinary shares	$	71,150	$	66,347	$	71,900	$	61,115